[FCS-27]Berkeley DB.
Merge branch 'master' into FCS-27
[FCS-27] Tests.
[FCS-27] DB object changed to DBWithCursor.
[FCS-27] DB clear, names changed.
[FCS-27] Task server DB changed to Berkeley DB.
[FCS-26] Improve load balance mechanism
[FCS-26] Improve load balance mechanism