Cleaned up GridFS
Cleaned up GridFS

refs hmarr/mongoengine#465

Davidrjx/mongoengine,larsbutler/mongoengine,muhammad-ammar/mongoengine,closeio/mongoengine,sourcelair/mongoengine,khallaghi/mongoengine,prijindal/mongoengine,ms5/mongoengine,gmacon/mongoengine,noirbizarre/mongoengine,ConsumerPhysics/mongoengine,losintikfos/mongoengine,MakerReduxCorp/mongoengine,depop/mongoengine-stripped,reallistic/mongoengine,elephanter/mongoengine,Catstyle/mongoengine,hmarr/mongoengine,gavincabbage/mongoengine,cogniteev/mongoengine,DavidBord/mongoengine,touilleMan/mongoengine,MongoEngine/mongoengine,MRigal/mongoengine,iandd0824/mongoengine,starsirius/mongoengine,nathanial/mongoengine,Multiposting/mongoengine,WingGao/mongoengine,nicolascine/mongoengine,jimmyshen/mongoengine,MakerReduxCorp/mongoengine,yarneo/mongoengine,ProgressivePlanning/mongoengine,Davidrjx/mongoengine,eli-b/mongoengine,RussellLuo/mongoengine,blaggacao/mongoengine,9nix00/mongoengine,cogniteev/mongoengine