This CL also adds a settings option to enable/disable an Emoji-ALT
physical key.

Bug: 18122464
Change-Id: Iee1d97efec979a902b0492071d5e511ca1792ff0

Bug: 18025209
Change-Id: Id8dbb051e04270f6892cae12a443103bd0d32dcb

Bug: 17942814
Change-Id: I0bbef716dff47ed8eb880209d448629ad853b904

- Adds a preference for enabling sync, which controls the sync behavior
- Make the ProductionFlags depend on appropriate flags to guarantee that
  we don't mess things when flipping some flags
- Preferences now control the "syncable" property of the provider
  thereby controlling the policy and when this entry shows up in
  system settings.

Bug: 17464069
Change-Id: I1d58351188518c1ae9f1f9e147b5ea15d32a3427

There are two categories of preferences:
1. That are part of the default shared preference
   They were all getting backed up and restored.
   Added a blacklist to not restore some of these.
   e.g. current account

2. That are in a non-default shared preference file.
   These are not getting backed up currently, but added a specific
   local preference file for all such preferences.

Bug: 17288591
Change-Id: I2f748be971a2337543e5014434aa39313fd1e1d8