L-BFGS-B Implementation

Very rough at the moment. Uploaded for potential comments/suggestions.

********* PEOPLE *************
Primary reviewer: @sc932 

Reviewers: @suntzu86 

********* DESCRIPTION **************
Branch Name: denizokt_228_implement_LBFGSB
Ticket(s)/Issue(s): Closes #228 

********* TESTING DONE *************
make test
Oh one more. For "significant" constants, write your comments like:
```
#: blah
#: foo
MY_CONSTANT
```
Then sphinx will doc it. And you can reference it in other docs by:
```
Isn't :const:`path.to.file.MY_CONSTANT` a cool constant?
```