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
here I'd also describe why 0.25 is the chosen value. That link describes what this is but it doesn't tell me the relevance of 0.25. iirc it's just a magic number in the UCB1-tuned algorithm. You might also change the name of the constant to reflect it's specific purpose in UCB1-tuned.