Drop the database on install failure

src/freedombone-app-gnusocial

     # check gnusocial has a config file
     gnusocial_config_file=/var/www/$GNUSOCIAL_DOMAIN_NAME/htdocs/config.php
     if [ ! -f $gnusocial_config_file ]; then
+        drop_database gnusocial
         rm -rf /var/www/$GNUSOCIAL_DOMAIN_NAME
         echo $'Gnusocial config.php not found'
         exit 87586

src/freedombone-app-postactiv

     # check postactiv has a config file
     postactiv_config_file=/var/www/$POSTACTIV_DOMAIN_NAME/htdocs/config.php
     if [ ! -f $postactiv_config_file ]; then
+        drop_database postactiv
         rm -rf /var/www/$POSTACTIV_DOMAIN_NAME
         echo $'Postactiv config.php not found'
         exit 87586