Add new API + version namespaces

Force a JSON response as default and pass API constraints to direct
requests to proper version of controllers
Add API key to for request authentication

Use Rails’ #authenticate_or_request_with_http_token to check for User
with specific API key found in header
Move controllers to version modules
Add API key to User factory
Namespace controller tests
Set http headers for authorization

Header sets basic authentication parameters for requests
Remove #new test

This will never be used within Rails itself
Use api params
Load batches of articles

Add scopes to Article model for limited loading
Remove redirection logic

Templates/routing will be extremely limited, if used at all since Rails
end is pretty much only going to be used for API calls.
Change old before_filter to new API version
Move users to API subfolder
Fix route tests/namespace controller
Move templates to api subfolder
Move sessions out of Api scope
Remove template

Now stored in API subfolder