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
you need to have:
```
``compute_*``
```
the star is how rst marks boldface or empahsis or something. If you have a star without a closing star, the docs will fail to render this text and complain.

if you haven't, I would run "make -B docs" in the MOE root directory. You should see 70 warnings at the end. If you have more, please identify and fix them in your text. It's also good to open up the locally generated docs (navigate to the file on your computer) and check a few places to see that the links came out correctly, things look right, etc.