Settings - update for new UI (no more Drawer)

- follow the UX spec by no more using a Drawer
- the Dashboard is now a Fragment that contains the list of Headers
- the search results are also put into a Fragment that is replacing
the initial one (Dashboard or other) when expanding the SearchView
- use a SearchView for query input
- when tapping on a Header or a Search Result, re-launch Settings as
an Activity so that we are benefiting from the Activity stack for
UP affordance and BACK button
- manage UP affordance to show it only when needed
- move some Actions to the Menu in the ActionBar for allowing space
to the Search action and removing some clutter
- fix an issue with the Index and WiFiEnabler and their cached Context
that was not updated when there was a Configuration change
- simplify the SettingsActivity code by extracting some inner classes

Change-Id: I50b5f77bb44a7fade1886114dbbc820609a5e63d
19 files changed