libtracker-miner: Removed TrackerCrawlFlags and use TrackerDirectoryFlags

This patch does the following things:
- The _NO_STAT flag has been added.
- The _FOLLOW_SYMLINKS flag has been added in the follow-symlinks branch and
  is not intended for this development cycle
- Remove TrackerDataProvider's _{get|set}_dir_flags() API (no longer used).
Release 1.1.4