Deprecation clean up.

Deprecated Methods to remove:

• bson._to_dicts
• bson.BSON.from_dict
• bson.BSON.to_dict
• pymongo.connection.from_uri
• pymongo.connection.paired

Deprecated method parameters to remove:

• pymongo.collection.__init__ - options
• pymongo.collection.create_index - deprecated_unique
• pymongo.collection.ensure_index - deprecated_unique
• pymongo.collection.group - command
• pymongo.collection.map_reduce - merge_output, reduce_output
• pymongo.database.create_collection - options