* MRC

	- replication flags of a replica in an X-Loc list are now persistently stored
	- Added support for replica selection policies. Such policies can be assigned at volume level and determine how replica lists that are returned to the client are ordered, so that the client can attempt to contact replicas in the natural order of the replica list. The default policy returns replica lists in the same order in which replicas were added. Additional policies can be implemented as built-in policies or used as custom policies with the policy plug-in mechanism.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@595 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534