Fix kwarg passing in combined example

********* PEOPLE *************
Primary reviewer: @suntzu86 

Reviewers: @yonromai

********* DESCRIPTION **************
Branch Name: sclark_test_new_pull
Ticket(s)/Issue(s): Closes N/A

This extends #355 by @yonromai and cleans up a few other cases where this could fail. It also extends the docs to make it more clear what is getting passed around.

********* TESTING DONE *************

Extended test.
make test
i think this should be mean_var_kwargs