Re-enable spam filtering - spamassassin now installs on jessie

src/freedombone

 }
 
 function spam_filtering {
-  # NOTE: spamassassin installation currently doesn't work, sa-compile fails with a make error 23/09/2014
   if [[ $SYSTEM_TYPE == "$VARIANT_CHAT" || $SYSTEM_TYPE == "$VARIANT_MEDIA" || $SYSTEM_TYPE == "$VARIANT_NONMAILBOX" ]]; then
       return
   fi
 install_watchdog_script
 configure_email
 create_procmail
-#spam_filtering
+spam_filtering
 configure_imap
 configure_gpg
 encrypt_incoming_email