Added selector argument to collection.update for mongolab-brain's save h...

The save handler for mongolab-brain is missing the "selector" argument when it calls mongodb's collection.update method to save data to mongolab. The call appears to succeed, but as a result the remaining arguments are mapped to the incorrect parameters; the data never actually makes it all the way to mongolab and therefore nothing persists.

Adding a selector argument (an empty selector, as used elsewhere in the script) fixes the problem, and data persists as it should.