Placeholder functions for app upgrades

src/freedombone-app-babel

 ENABLE_BABEL="no"
 BABEL_PORT=6696
 
+function upgrade_babel {
+    echo ''
+}
+
 function backup_local_babel {
     echo ''
 }

src/freedombone-app-batman

 	echo 'configure_firewall_for_batman' >> $COMPLETION_FILE
 }
 
+function upgrade_batman {
+    echo ''
+}
+
 function backup_local_batman {
     echo ''
 }

src/freedombone-app-blog

 MY_BLOG_TITLE="My Blog"
 MY_BLOG_SUBTITLE="Another ${PROJECT_NAME} Blog"
 
+function upgrade_blog {
+    echo ''
+}
+
 function backup_local_blog {
     echo ''
 }

src/freedombone-app-cjdns

 CJDCMD_REPO="https://github.com/inhies/cjdcmd"
 CJDCMD_COMMIT='973cca6ed0eecf9041c3403a40193c0b1291b808'
 
+function upgrade_cjdns {
+    echo ''
+}
+
 function configure_firewall_for_cjdns {
 	if grep -Fxq "configure_firewall_for_cjdns" $COMPLETION_FILE; then
 		return

src/freedombone-app-dlna

 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+function upgrade_dlna {
+    echo ''
+}
+
 function configure_firewall_for_dlna {
 	if grep -Fxq "configure_firewall_for_dlna" $COMPLETION_FILE; then
 		return

src/freedombone-app-emacs

 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+function upgrade_emacs {
+    echo ''
+}
+
 function backup_local_emacs {
 	echo ''
 }

src/freedombone-app-gnusocial

 SHARINGS_THEME_REPO="http://git.lasindias.club/manuel/SharingsTheme"
 SHARINGS_THEME_COMMIT='7106c7ef03'
 
+function upgrade_gnusocial {
+    echo ''
+}
+
 function backup_local_gnusocial {
 	echo ''
 }

src/freedombone-app-gogs

 GIT_ADMIN_PASSWORD=
 GOGS_COMMIT='3fb4f7f4980b4339fd9ef6a3ba5b0acab83d264d'
 
+function upgrade_gogs {
+    echo ''
+}
+
 function backup_local_gogs {
     echo ''
 }

src/freedombone-app-hubzilla

 HUBZILLA_COMMIT='2d79e75788aa71664a379c4cea0b6bfe3ab87ad0'
 HUBZILLA_ADDONS_COMMIT='67b40c7a40f328a93ee030eb15e9e1261f3cba64'
 
+function upgrade_hubzilla {
+    echo ''
+}
+
 function backup_local_hubzilla {
     echo ''
 }

src/freedombone-app-ipfs

 IPFS_COMMIT='20b06a4cbce8884f5b194da6e98cb11f2c77f166'
 IPFS_PORT=4001
 
+function upgrade_ipfs {
+    echo ''
+}
+
 function backup_local_ipfs {
     echo ''
 }

src/freedombone-app-irc

 # An optional password to log into IRC. This applies to all users
 IRC_PASSWORD=
 
+function upgrade_irc {
+    echo ''
+}
+
 function backup_local_irc {
 	echo ''
 }

src/freedombone-app-mediagoblin

 MEDIAGOBLIN_ADMIN_PASSWORD=
 MEDIAGOBLIN_ONION_PORT=8096
 
+function upgrade_mediagoblin {
+    echo ''
+}
+
 function backup_local_mediagoblin {
     echo ''
 }

src/freedombone-app-mumble

 VOIP_DATABASE="mumble-server.sqlite"
 VOIP_CONFIG_FILE="mumble-server.ini"
 
+function upgrade_mumble {
+    echo ''
+}
+
 function backup_local_mumble {
     echo ''
 }

src/freedombone-app-rss

 RSS_READER_GNUSOCIAL_REPO="https://github.com/bashrc/ttrss-gnusocial"
 RSS_READER_GNUSOCIAL_COMMIT='8b92b8f5db7b0d12459c7bd86a50f48815efe642'
 
+function upgrade_rss {
+    echo ''
+}
+
 function backup_local_rss {
 	echo ''
 }

src/freedombone-app-searx

 SEARX_LOGIN_TEXT=$"Search engine login"
 SEARX_PASSWORD=
 
+function upgrade_searx {
+    echo ''
+}
+
 function backup_local_searx {
 	echo ''
 }

src/freedombone-app-sip

 VOIP_TURN_TLS_PORT=5349
 VOIP_TURN_NONCE=
 
+function upgrade_sip {
+    echo ''
+}
+
 function backup_local_sip {
 	echo ''
 }

src/freedombone-app-syncthing

 SYNCTHING_SHARED_DATA=/var/lib/syncthing/SyncShared
 SYNCTHING_USER_IDS_FILE='.syncthingids'
 
+function upgrade_syncthing {
+    echo ''
+}
+
 function backup_local_syncthing {
     echo ''
 }

src/freedombone-app-tox

 TOXIC_COMMIT='cf16849b374e484a33a4dffa3dfb937b59d537f2'
 TOXIC_FILE=/usr/local/bin/toxic
 
+function upgrade_tox {
+    echo ''
+}
+
 function backup_local_tox {
 	echo ''
 }

src/freedombone-app-vpn

 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+function upgrade_vpn {
+    echo ''
+}
+
 function backup_local_vpn {
 	echo ''
 }

src/freedombone-app-webmail

 WEB_PATH=/var/www
 WEBMAIL_PATH=$WEB_PATH/webmail
 
+function upgrade_webmail {
+    echo ''
+}
+
 function backup_local_webmail {
     echo ''
 }

src/freedombone-app-wiki

 WIKI_CODE=
 WIKI_ONION_PORT=8089
 
+function upgrade_wiki {
+    echo ''
+}
+
 function backup_local_wiki {
     echo ''
 }

src/freedombone-app-xmpp

 XMPP_CIPHERS='"EDH+CAMELLIA:EDH+aRSA:EECDH+aRSA+AESGCM:EECDH+aRSA+SHA256:EECDH:+CAMELLIA128:+AES128:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!IDEA:!ECDSA:kEDH:CAMELLIA128-SHA:AES128-SHA"'
 XMPP_ECC_CURVE='"secp384r1"'
 
+function upgrade_xmpp {
+    echo ''
+}
+
 function backup_local_xmpp {
 	echo ''
 }

src/freedombone-app-zeronet

 ZERONET_ID_REPO="https://github.com/HelloZeroNet/ZeroID"
 ZERONET_ID_COMMIT='ccf14fdc96fa9cdb2ddd8a7ab283a8e17a4f234b'
 
+function upgrade_zeronet {
+    echo ''
+}
+
 function backup_local_zeronet {
 	echo ''
 }

src/freedombone-tests

 	fi
 
 	# check that these functions exist
-	interface_functions=( install remove backup_local backup_remote )
+	interface_functions=( install remove backup_local backup_remote upgrade )
 
 	# for all the app scripts
 	for filename in $FILES