PRF : add faster class method
PRF : add faster class method

Add a class method to construct a Document based on a raw pymongo
response (instead of a MongoEngine document).

hhslepicka/metadatastore,hhslepicka/metadatastore,arkilic/metadatastore,tacaswell/metadataStore,ericdill/databroker,NSLS-II/metadatastore,arkilic/metadatastore,NSLS-II/metadatastore,tacaswell/metadataStore,ericdill/databroker