Added an API for the hypervisor planner.

The API returns a JSON object with the necessary data.

Also, I fixed the Gemfile to build known-working versions of each module
needed for this project.
Merge pull request #25 from bnied/master

Added Hypervisor Planner API
Speed up the active nodes route.

It is much faster create a lookup hash based off a single elasticsearch
query.
eager load the pod table and use yajl
Expand the location support for utilization.

This allows us to leverage Optopus' location support to provide the
following:

- Create/destroy locations via the UI.
- See hypervisor utilization per location.
- API hook for HV utilization.