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 *************
Better if this read from:  ENDPOINT_TO_DEFAULT_OPTIMIZER_TYPE