mno-async_writes/client: Added TestEnvironment class to common test code which...

mno-async_writes/client: Added TestEnvironment class to common test code which aggregates Client and Test Server objects and can be used by unit tests.

git-svn-id: https://xtreemfs.googlecode.com/svn/branches/mno-async_writes@2971 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534