Version bump to 0.2.0
Added jsonifier module

This module converts objects to json based on a supplied list of
methods. The list is either a blacklist or a whitelist.
It lets us return more in our json than just what the api included.
Added convenience methods to Jsonifier

jsonify_only :foo #whitelists method foo
jsonify_all_except :foo, :bar #blacklists foo and bar
Refactored jsonifier
Track class now includes Jsonifier

We can now call #to_json and get json output that includes custom
methods from this class.