Added Bandit BLA implmentation

********* PEOPLE *************
Primary reviewer: @sc932 

Reviewers: @suntzu86 

********* DESCRIPTION **************
Branch Name: norases_373_bla_bandit
Ticket(s)/Issue(s): #373 

********* TESTING DONE *************
make test
make style-test
I'd also spell out what "BLA" stands for. If you google for like "BLA bandit" the results are wholly unrelated.
Same thing for UCB if you dont' mind going back and editing those docs.