feat(client:auth): add first type definition (callback: Function)

Author: Awk34

Diff for: app/templates/client/components/auth(auth)/auth.service.js

@@ -20,7 +20,7 @@ function AuthService($location, $http, $cookies, $q, appConfig, Util, User) {
      * @param  {Function} callback - optional, function(error, user)
      * @return {Promise}
      */
-    login({email, password}, callback) {
+    login({email, password}, callback: Function) {
       return $http.post('/auth/local', {
         email: email,
         password: password