xtfs_test: streamlining some tests, making --autotest an explicit option,...

xtfs_test: streamlining some tests, making --autotest an explicit option, adding support for testing other servers



git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@639 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534