Added Bandit UCB1 implementation

********* PEOPLE *************
Primary reviewer: @sc932 

Reviewers: @suntzu86 

********* DESCRIPTION **************
Branch Name: norases_354_ucb1_bandit
Ticket(s)/Issue(s): #354 

********* TESTING DONE *************
make test
make style-test
could be list comprehensioned:
```
[arm_name for arm_name, sampled_arm in arms_sampled.iteritems()
  if sampled_arm.total == 0]
```
(fix indenting)