Endless/infinate change list; Pull to refresh

Scrolling to the bottom of the change list will send a request
 to load more changes if there are any more to be loaded.

Full list of changes:

Add before and after search keywords as aliases for age searching. The
 mimimum server version for these is v2.8.2. This will allow fetching
 changes to work with stable v2.8.1 releases and will switch over to the
 newer searching operators when the next Gerrit version is released
 (even if it is v2.9 or v3.0).
Improve server version checking
Pass processed intent as extra into Finished message
Remove unused GerritTask class
Close open cursors when finished in database methods
Limit the max number of changes to fetch at once to 100
Detect and block duplicate syncs - don't process new requests
 when the URL is identical to one already being processed
Fix marking of more changes in database

GerritURL: Use search keywords instead of project/owner/changeid field
 variables; add copy constructor
Tools: Change toggleAnimations to return the top adapter
ProjectSearch: URL encode project's Gerrit query
ChangeListProcessor: Use direction when determining if sync required
GerritSearchView: Add method to obtain keywords
AgeSearch: Fix issue in timestamp parsing
SearchKeyword: Trim quotes off parameter; make parcelable
SyncProcessor: Added abstract method to get the number of items fetched;
 added context as a parameter to isSyncRequired; add null checks on the
 resulting data; pass intent to constructor; insert returns number of
 rows updated.
DatabaseFactory: Change insert method to return whether the db changed.

PS2: EndlessAdapter: Implement disabled state
AgeSearch: Delegate before and and after Gerrit query generation to
 BeforeSearch and AfterSearch classes; Fix instant formatting;
 Add comparitor
SearchKeyword: Add some more helper functions
GerritURL: URL encode search keywords

PS3: Always enable endless list adapter

PS4: Swipe Refresh view
Use status colours and transparent for the SwipeRefreshLayout's colour
 indicators. These are theme-independant colours.
Fix url limit param & Gerrit query for relative age searching
GerritService: Block sync when syncing same status changes

Change-Id: I282e235e7af78d6ea9903a5b153c6bacd94641ef