move old python stuff to legacy
add script to find allreferenced hashes
FIX: close processed leaf catalogs to save file descriptors
add script to retrieve catalog statistics
add script to retrieve root hash and timestamp
add wrapper script to collect repo HEAD statistics
add human readable output to get_info.py
Merge pull request #558 from reneme/addon-python_tools

Add-On: Python Tools based on CVMFS Python Library

This deprecates the python debug tools in add-ons/tools and replaces them by some new scripts that are based on the CVMFS python library in python/. I will add more of those scripts opportunistically as soon as I need them. For now there are some statistics gathering tools:
    get_info.py - retrieve the internal catalog statistics for the current root catalog of a repository
    get_root_hash.py - find the current root catalog hash of a repository
    get_referenced_hashes.py - walk the full catalog tree of a repository and list all referenced hashes
    get_head_statistics.h - a combination of the scripts above