Adds NG states

This PR adds the ng states for the nginx formula. This changes the pattern considerably and adds support for managing virtual hosts files. In the interest of disclosure, there are a couple caveats:

- ng requires the merge parameter of salt.modules.pillar.get(), not formally available until Helium. This is explicitly noted in the README
- Much of the vhost management is clumsily done as a state and should have been implemented as an addition to the nginx execution module (and by extension, as a state module). Unfortunately, realized that a bit too late to reverse course this time around.
- There's a ton of reliance on jinja underneath the hood making it both complex and difficult to read but that's all to the benefit of making the pillar (the true user-interface), powerful, extensible, and intuitive