Implement Epsilon-First bandit endpoint

********* PEOPLE *************
Primary reviewer: @sc932

Reviewers: @suntzu86

********* DESCRIPTION **************
Branch Name: norases_335_create_epsilon_first_bandit_endpoint
Ticket(s)/Issue(s): Closes #335

********* TESTING DONE *************
make test
make style-test
I spoke with @sc932. He indicates there are more epsilon policies than molecules in the universe and we dont' want to be creating separate endpoints for all of them.

Your solution is totally appropriate, nevermind!