Updates deb package scripts.

debian/jitsi-meet-prosody.postinst

 
         . /etc/default/jitsi-videobridge
 
-        if [ -x /etc/prosody/prosody.cfg.lua ]; then
+        if [ -f /etc/prosody/prosody.cfg.lua ]; then
             mv /etc/prosody/prosody.cfg.lua /etc/prosody/prosody.cfg.lua.orig
         fi
         gunzip -c /usr/share/doc/jitsi-meet-prosody/prosody.cfg.lua-jvb.example.gz > /etc/prosody/prosody.cfg.lua

debian/jitsi-meet-prosody.postrm

 
 
 case "$1" in
-    purge|remove)
+    remove)
         if [ -x "/etc/init.d/prosody" ]; then
             invoke-rc.d nginx reload
         fi
     ;;
 
-    upgrade|failed-upgrade|abort-install|abort-upgrade|disappear)
+    purge|upgrade|failed-upgrade|abort-install|abort-upgrade|disappear)
     ;;
 
     *)

debian/jitsi-meet.postrm

 
 
 case "$1" in
-    purge|remove)
+    remove)
         if [ -x "/etc/init.d/nginx" ]; then
             invoke-rc.d nginx reload
         fi
     ;;
 
-    upgrade|failed-upgrade|abort-install|abort-upgrade|disappear)
+    purge|upgrade|failed-upgrade|abort-install|abort-upgrade|disappear)
     ;;
 
     *)