RebindOptions: declare fields public
Extracts AbstractBlueprintTest and marks MongoDbBlueprintTest as WIP
This closes #345
MongoDB replica set improvements

* Initial size is 3 if unspecified
* Uses BrooklynAccessUtils to configure addresses and ports
* Fixes a number of integration tests
MongoDBServer uses configuration with smallfiles and noprealloc

"Leaner and meaner", as according to MongoDB/Docker documentation.
Adds URL constructor to BrooklynApi
Node entity ensures NPM's modules are on NODE_PATH