Update operations.cpp
Update main.cpp
Fix some build problems on Linux.
Merge branch 'master' of https://github.com/epitron/gridfs-fuse

Conflicts:
	Makefile
Merge branch 'master' of https://github.com/oomathias/gridfs-fuse
Fix use of ScopedDbConnection for MongoDB 2.2+.

Use static class methods to construct ScopedDbConnection objects and later delete them.
However, 2.5 seems to return to public constructors.