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
yes I tested edge cases and a value that is in the middle. Added DEFAULT_EPSILON.