* new MRC: made some modifications to the storage backend

  - some refactoring was necessary to set the stage for restoring DB dumps
  - the backend now uses direct BabuDB lookups for performance reasons
  - ensured that 'stat' no longer returns negative access modes
* MRC unit test now tests the new MRC

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@88 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534