Fix Versioning

[ethanmick]

Give it a good way to version the API easily.

[ethanmick]

The objective of this is such: We want to be able to break backwards compatibility while never forcing clients to upgrade.

This will allow us to change the functionality of a route without needing to create a new route. To do this, we will have the version specified in the request, which API version to hit.

The two main ways of doing this is with:

• a v[0-9] in the url
• a Header which specifies the API Version.

A header can be nice, because if it's not sent, it will default to the latest version. URL's, you have to be explicit. Once you choose your scheme, we will need to move away from Heroku, and setup a server with Nginx in front. Nginx will check the version and direct the request to the appropriate running instance.

This means we will need multiple running servers, but we can simple branch off versions and keep working on master.

As such, you can expect in the future:

• master is the latest release. Not versioned yet, but in testing/released.
• develop is where all current development is happening, and the build may be broken.
• API version branches (and tags) are frozen, except for critical bug fixes.