Dev releases are listed as 'unknown' instead of 'not opted in'

Dev releases are not covered by the Drupal security policy, so should be grouped with the other modules that are not opted in. Dev versions (e.g. 1.0.x-dev) are never listed as releases in the release history XML, so $found stays FALSE and they fall into the "Unknown / Unable to find release information" bucket instead of "Not opted-in".

The fix is to detect dev versions before making the API call and short-circuit them straight to $not_covered