Fixes to make SO login work. GitHub now works also (was a FF plugin bug)

sideload/socialnorm/github/src/GitHubProvider.php

@@ -1,5 +1,6 @@
 <?php namespace SocialNorm\GitHub;
 
+use SocialNorm\Exceptions\AuthNotUsableException;
 use SocialNorm\Exceptions\InvalidAuthorizationCodeException;
 use SocialNorm\Providers\OAuth2Provider;
 
@@ -15,7 +16,8 @@ class GitHubProvider extends OAuth2Provider
     protected $headers = [
         'authorize' => [],
         'access_token' => [
-            'Accept' => 'application/json'
+            'Accept' => 'application/json',
+            'Content-Type' => 'application/x-www-form-urlencoded'
         ],
         'user_details' => [
             'Accept' => 'application/vnd.github.v3'
@@ -72,10 +74,13 @@ class GitHubProvider extends OAuth2Provider
     protected function getPrimaryEmail($emails)
     {
         foreach ($emails as $email) {
-            if ($email['primary']) {
+            if ($email['primary'] && $email['verified']) {
                 return $email['email'];
             }
         }
+        if (!$emails[0]['verified']) {
+            throw new AuthNotUsableException("No verified e-mail.");
+        }
         return $emails[0]['email'];
     }