client:

- Fixed broken FileHandleImplementation::PingReplica (fixing error "The XtreemFS call failed: Unknown error: message is not valid. Not all required fields have been initialized: file_id, file_credentials.xcap").
- Added transfer strategies to AddReplica() call in xtfsutil - otherwise OSD did complain about missing strategy if read-only replication policy is set (error: "Set Replication Strategy not known (1).")
- Both changes fix issue 212.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@2706 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534