project: Use org.gnome prefix in app id and adapt to changes

In preparation to moving to GNOME all the IDs, DBus object paths, etc should
change.

Closes #303

data/org.gnome.Calls.desktop.in

@@ -0,0 +1,16 @@
+[Desktop Entry]
+Name=Calls
+GenericName=Phone
+Comment=A phone dialer and call handler
+# Translators: These are desktop search terms. Do not translate semicolons, end line with a semicolon.
+Keywords=Telephone;Call;Phone;Dial;Dialer;PSTN;
+# Translators: Do NOT translate or transliterate this text (this is an icon file name)!
+Icon=org.gnome.Calls
+TryExec=gnome-calls
+Exec=gnome-calls %u
+Type=Application
+StartupNotify=true
+Terminal=false
+Categories=Network;GNOME;GTK;Telephony;
+MimeType=x-scheme-handler/tel;x-scheme-handler/sip;x-scheme-handler/sips
+X-Purism-FormFactor=Workstation;Mobile;