Added Bandit UCB1-tuned implementation

********* PEOPLE *************
Primary reviewer: @sc932 

Reviewers: @suntzu86 

********* DESCRIPTION **************
Branch Name: norases_366_ucb1_tuned_bandit
Ticket(s)/Issue(s): #366  

********* TESTING DONE *************
make test
make style-test
I like the idea of failing when the user does something that is impossible
(Like UCB1 and specifying variance)
This is much better than taking in variance, dropping it on the floor, and not telling anyone. Maybe make a whitelist/blacklist of bandits that can take variance (or ones that dont)? BANDITS_WITH_VARIANCE = frozenset(...)