Only run POD tests in release testing
Comment this.
Remove API change warning.

It's been nearly a year since that change now.
Ensure username / password are not refs.

Handle the potential for JSON SQL injection.

As per the comment, if the username and password were deserialised from a JSON
request body, rather than form params, it's possible that they could be
hashrefs, instead of the straight scalars we'd expect.  And, if that hashref was
e.g. `{ '-like' => '%' }`, and was passed to a provider that uses a database
which in turn passed it to e.g. SQL::Abstract, we could end up with SQL rather
different to what we expected, matching more than we'd want.

So, check first that the username and password are straight scalars.
Merge branch 'master' of github.com:bigpresh/Dancer-Plugin-Auth-Extensible