tests:

xtestenv: Display help text if no parameters given.
xtestenv: Check return value of xtfsutil and mkfs calls and stop if error occured.
xtestenv: Readded feature to clean test directory (now called --clean-test-dir)
xtestenv: Added SO_REUSEADDR socket option to free port test to ensure that ports can be immediately reused.
xstartserv: Fixed classpath for server calls.
test scripts: Added test which checks the behaviour of adding and deleting partial and full replicas of the read-ony replication.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@2738 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534