Use content negotiation in AuthController

- Added zf-content-negotiation rules for AuthController in
  configuration.
- Modified controller to return a zf-content-negotiation ViewModel from
  the authorize and receive-code actions, and set that up to specify the
  template properly (and as documented).
Use the template identifiers in the documentation

- Altered the setTemplate calls to use the identifiers listed in the
  documentation, namely `oauth/authorize` and `oauth/receive-code`.
- Added a template map to the configuration, as those paths will not
  currently be found otherwise.
Merge branch 'hotfix/content-negotiation-template'

Close #58