oauth2server: authorization flow bug fixes

* Adds redirect URI field to application form.

* Adds validation and setters of redirect uris on model.

* Fixes issue in auth flow when validating scopes.

* Fixes template and context issues in 'Authorize application' view.

* Disables https redirect uri checking when in debug mode.

* NOTE Fixes auth flow issue by changing default value for
  Client.is_confidential. Upgrade included to update existing
  applications.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
oauthclient: error handling fix

* Fixes use of wrong exception type.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>