Moved declaration of iterator to top of block because Visual Studio refuses to compile C file with declaration in the middle
Added code with enhanced GridFS. Added tests for random writing
Added changes to gridfs.h
Added to bson.h macros to initialize bson objects and iterator
Merge pull request #101 from jsbattig/mongo-master-pull-request-gridfs

gridfs enhancements to support full random reading and writing and chunk pre/post processing