Bug fix in enrollment form

By mistake, we used TokenLoginForm instead of EnrollTokenForm(),
which worked until we renamed login tokens to access codes :)

owl.py

@@ -203,7 +203,7 @@ def enroll():
     if not have_session_p():
         return login_redirect(current=True)
 
-    form = TokenLoginForm()
+    form = EnrollTokenForm()
 
     if not form.validate_on_submit():
         return render_template('join.html', form=form, error=None)