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
the idea is if your objective fcn has outside parameters or whatnot, you can pass them through as kwargs and we'll just keep passing them along.

creating functors is generally a better solution but scipy does this too.