Added Bandit epsilon-greedy implementation

********* PEOPLE *************
Primary reviewer: @sc932

Reviewers: @suntzu86

********* DESCRIPTION **************
Branch Name: norases_255_create_epsilon_greedy_bandits
Ticket(s)/Issue(s): Closes #255 

********* TESTING DONE *************
make test-no-tox
make style-test-no-tox
you might want to do a copy.deepcopy here. right now, ```_historical_info``` is the same object as ```historical_info``` and if this bandit (or any subclass) edits it, probably unexpected behaviors will arise.

otherwise just be very very certain that ```_historical_info``` is always treated READ-ONLY