Hook up BFGS to rest

********* PEOPLE *************
Primary reviewer: @sc932 

Reviewers: @suntzu86 

********* DESCRIPTION **************
Branch Name: denizokt_285_qei_rest
Ticket(s)/Issue(s): Closes #285 

********* TESTING DONE *************
so this one is a little more complicated. the thing is, the cpp interfaces are different from the python interfaces for the parameter structs. for now, i could create another if statement (sacrificing some DRYness) but and tag the appropriate ticket (because i think it's something on eric's queue)