getToken(id: string, password: string): Observable<User> {
    let headers = new Headers({ 'X-Auth-User': id, 'X-Auth-Key': password });
    return this.http
        .get(url + 'auth', { headers: headers })
        .map(response => {
            let user: User = response.json() as User;

            // store user details and jwt token in local storage to keep user logged in between page refreshes
            localStorage.setItem('currentUser', JSON.stringify({ user: user, token: response.headers.get('X-Auth-Token') }));

            return user;
        })
   }// Get authorization token