Support legacy change details

TheApplication: Request server version when Gerrit changes
SyncProcessor: Use same request queue for all syncs
VersionProcessor: Better extraction of version number
Changes card: Ensure the server supports diffs before showing the dialog
Add support for using the legacy method of getting change details from
 the 'query changes' endpoint.
Merge StaticWebAddress into GerritURL
GerritURL: Self-manage gerrit base URL
Add new legacy commit details processor
Note: With this commit, change details for Omni are now supported.

Change-Id: I28f3c7d024c13d90836627799dca1507e21ab800