(maint) Test for created objects in 201 responses.

We weren't testing that 201 responses for node and group creation return
the created object in their bodies, so add tests for those.

Remove all uses of clojure.walk/keywordize-keys from the http tests;
instead just instruct chesire's json parse function to keywordize the
keys when parsing.

Also remove a println from the http tests.
(NC-130) Add API docs.

Add documentation for the routes & allowed methods that currently exist;
namely creating and retrieving nodes, environments, and groups; creating
rules; and retrieving classes and node classifications.

It is possible currently to create classes through the API, but this
mainly exists to allow us to test the API. Once we can receive class
information directly from Puppet, we will only be using those class
definitions and that API route will disappear. Therefore, the
documentation does not cover the class creation operation.
(maint) Don't look for node when classifying.

There's no further information that the node object in the database
could give us, since the only attribute of a node is its name which is
supplied in the request.
Merge pull request #18 from aperiodic/nc-130-api-docs

Add API Docs