LU-911 obdclass: new context tags for future use

LU-911 obdclass: new context tags for future use

- Add new thread tags: local, mgs and osp
- use LCT_LOCAL to avoid extra keys allocation when just local
  server update is needed.
- target_recovery_thread() is capable to serve OFD.

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: Ic41673c91b8d519c95a8740c418070f9e14aa3a6
Signed-off-by: Mikhail Pershin <tappro@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/1851
Tested-by: Hudson
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>