Don't enforce required and current scopes to be same size

Instead require the current scopes only contain all the
required scopes

Author: kevinsawicki

app/src/main/java/com/github/mobile/accounts/AccountAuthenticator.java

@@ -102,10 +102,7 @@ private boolean isValidAuthorization(final Authorization auth,
             return false;
 
         List<String> scopes = auth.getScopes();
-        if (scopes == null || scopes.size() != requiredScopes.size())
-            return false;
-
-        return scopes.containsAll(requiredScopes);
+        return scopes != null && scopes.containsAll(requiredScopes);
     }
 
     private Intent createLoginIntent(final AccountAuthenticatorResponse response) {