basic chat support with gnome 3.8
Change metadata shell version to 3.8
Check for photo before unpacking
Use disconnectSignal for handler registered with connectSignal
TextureCache.load_icon_name was removed...
Seems like the SearchProvider class disappeared too...
Woot? New API, out of the blue
source: factor out code dealing with avatar picture

The new function will be reused from the search provider.
source: chatstate value fix
search provider: port to 3.8
Eliminate tabs and trailing white spaces
Licensing under GPL3, fixes #8