Multiple projection with same prefix: last projection is the only that survives

When asking multiples projections that had the same prefixes
(eg: "a.b.c", "a.b.d") only the last projection survive.
This is not the expected behaviour in mongo.

The solution is try to reuse the the result values.
Merge branch 'projection-multiple-nested-with-same-prefix' of git://github.com/zauberlabs/fongo into zauberlabs-projection-multiple-nested-with-same-prefix

Conflicts:
	src/main/java/com/mongodb/FongoDBCollection.java