tests: incorporated JUnit tests into XtreemFS test suite

* added offset to all ports used by JUnit tests in order to avoid port collisions w/ integration tests
* merged and adapted JUnit test script from 'jan-xtreemfs-snapshots' branch

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@3469 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534