added COBYLA (no REST interface yet)

********* PEOPLE *************
Primary reviewer: @sc932 

Reviewers: @suntzu86 

********* DESCRIPTION **************
Branch Name: denizokt_370_constraints
Ticket(s)/Issue(s): Closes #370 

********* TESTING DONE *************
make test
make style-test
does cobyla not return numpy arrays?  if there is so much variation in the output of scipy optimizers, then disregard the comment about just constructing arg-lists and you might as well make this optimize method abstract and overridden in subclasses