Remove in-memory cache of tm2z sources.
Merge pull request #76 from mapbox/nocache

Remove in-memory cache of tm2z sources
2.3.0
Add (failing) test for loading tm2z for string uri.
url.parse() string uri passed directly to tm2z loader.
Merge pull request #77 from mapbox/tm2z-uri-string

tm2z direct load of string uris
2.3.1
Merge branch 'master' into mapnik3