Remove Perl Test Environment

This removes the perl dependency of the integration test system together with the perl mock services. There will be further Pull Requests, to rebuild the provided functionality in a leaner fashion (i've just deleted 124.000 LOC of external perl modules in our source tree).

**Note:** Tests 515 and 516 stay untouched on purpose, since they are replaced by [another Pull Request](https://github.com/cvmfs/cvmfs/pull/225).