/**
   * Retrieve a specific category based on Id
   * @param id
   * @returns {Observable<R|T>}
   */
  public getCategory(id: number): Observable<Category> {
    const params: URLSearchParams = new URLSearchParams();
    params.set('id', id + '');
    const headers: Headers = new Headers();
    headers.append('Accept', 'application/json');
    headers.append('Authorization', 'Bearer ' + this.authenticationservice.getSessionToken());
    headers.append('Content-Type', 'application/x-www-form-urlencoded');

    return this.http.get(this.endpoints.getCategory, {search: params, headers: headers})
      .map(this.extractData)
      .catch(this.handleError);
  }