Change list searching

Tested that search query text is correctly processed and a database query can
 be formed.
Added change list querying methods
Moved the content observer in UserChanges to separate class file.
Unbind any previous cards before trying to add new ones
Use a layout change listener to (un)hide items in the overflow when
 there is not enough room.
Search when query is submitted and when the query is empty
CardsFragment: Loader accepts database query (where and bindargs) directly
Manifest: Add searching and cleanup
GerritControllerActivity: Style fixes
Cleanup variables
ProjectsList: Remove redundant conditional

~Fix conflicts

Change-Id: I8e6ee93cc5da91af2c77ac7706f15a7eb7000413