Add simple tokumx collector (based off mongodb collector)

TokuMX is a MongoDB fork based on TokuTek's fractal tree data structure. This fork add a `engineStatus` command that gives insight into many internal metrics of the database that may be helpful in diagnosing problems and monitoring the overall health of the system.

This is a collector that adds metrics specific to tokumx. I have basically taken the mongodb collector and simply added the results of `db.engineStatus()` to the `db.serverStatus()`. 
Please refer to the user guide at [TokuMX website](http://www.tokutek.com/products/tokumx-for-mongodb/) for more information.