Nic::BMC CRUD and proxy operations API

This is an extension to the foreman API that allows users to perform operations on their interfaces, just BMC as of now, but it's easily extensible. In addition to that, it also allows users to create/show/update/delete BMC interfaces associated to hosts, which in turn makes massive installations of physical machines in foreman with these interfaces significantly easier.

Calls should be done to /api/hosts/:host_id_or_name/interfaces as explained in app/controllers/api/v2/interfaces_controller.rb, power operations for instance go like
```
PUT api/hosts/:host_id_or_name/interfaces/:interface_id/power  , { "power_action" : "cycle" }
```