prepare scmongo import to scrapylib
scrapylib.httpcache.MongoCacheStorage

Merge scrapylib into mongocache
add auth
Merge pull request #3 from t1h/add-auth

add auth
removed deprecated scrapy.conf import

and disable middleware on missing pymongo module
(Re-)Added sharded operation to MongoCacheStorage

allowing to use one Collection per Spider if enabled (old behaviour).
Merge Mongo connection authentication
doing trivial API change to MongoClient
Adding some verbosity to MongoCacheStorage