Feature: Extended .cvmfsdirtab

This allows for wildcards in the `.cvmfsdirtab` file. Additionally it changes the behaviour a little bit: When finding a non-applicable `.cvmfsdirtab`-rule it does not stop anymore but only prints a warning.

**Note:** There is an integration test but it currently fails due to [CVM-608](https://sft.its.cern.ch/jira/browse/CVM-608).