View: added frame around avatars

Fixed: https://bugzilla.gnome.org/show_bug.cgi?id=727847
build: move resource files into data subdir
build: moved css tweaks from gnome-themes-standard

It's easier to fix styling issues if the css code is hosted at
gnome-contacts git repository
UI: removed double strokes on Contacts.Window

Removed double strokes around Contacts.ListPane and Contacts.ContactPane

Fixed: https://bugzilla.gnome.org/show_bug.cgi?id=727803
ListPane: moved signal connection to ui file
styling: removed unused css rules
Contact: remove unused method