FIX: API Adaptions for the new History Module

This adapts code locations that were using the old `TagList` interface of the history database. After this Pull Request is merged, the code should compile again. Sorry for this, but separating the changes with functional stages would have been a major head ache.

Note: This contains [Rewrite: Named Snapshot History Management Class](https://github.com/cvmfs/cvmfs/pull/591), [Rewrite: Swissknife History Integration](https://github.com/cvmfs/cvmfs/pull/592) and [Refactor: cvmfs_server Named Snapshot Management](https://github.com/cvmfs/cvmfs/pull/593).
Would be good to test removing multiple tags in a single command, too