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 *************
this was originally what i intended to do, but now i fixed it (from below). lbfgsb is much slower than gradient descent (at least given the same # of multistarts)