Feature/install opentripplanner

I think it would be best to have `- hosts: vagrant` here.

My reasoning for this is that Ansible is so flexible in terms of variable definitions and overrides that it's easy to end up with spaghetti if we don't impose some kind of system on top of it. What we did on BCG that I think worked well was to use `hosts` to define our concept of physical machines, and `roles` to specify the Ansible tasks that target each machine. My feeling is that things get messy if we try to define hosts in terms of abstract concepts such as "app server" once we get to the point where we have an app server on Vagrant, an app server on Jenkins, and a production app server, all with slightly different sets of variables. If hosts correspond (roughly) to physical machines then it's easy to override role defaults inside of `group_vars` files, which limits the number of sources of variable definitions and keeps things cleaner.

Happy to hear other thoughts about this, I don't think we've ever specifically discussed the preferred organization system for this stuff.