[1.8] Added local settings support

How to use:

1) Put schemas in ~/.local/share/cinnamon/schemas/
2) Run glib-compile-schemas ~/.local/share/cinnamon/schemas/ (without sudo!)
3) Replace

     Gio.Settings({schema: SCHEMAS})

with

     global.get_local_settings_from_id(SCHEMAS)


Known issues: If schemas is put in /usr/share/glib-2.0/schemas/ instead, Cinnamon crashes. Code should cater for both situations.