Public docker image live, updated docs

********* PEOPLE *************
Primary reviewer: @suntzu86 

Reviewers:

********* DESCRIPTION **************
Branch Name: sclark_332_set_up_public_docker
Ticket(s)/Issue(s): Closes #332 

********* TESTING DONE *************

Tested on dev and personal linux box
MOE v1.3.4 will be already built and in dockerhub. This will only vanish if we kill our dockerhub account, in which case everything dies.

We will make sure all future min_reqs are a superset of current reqs.