Install PasswordLib via Composer
add namespace to ErrorController
update afutseng's pixframework patch to support ErrorController using namespace via Composer
Add AlertException and views
Add PasswordAuthenticationService
implement Login feature
Merge branch 'master' of github.com:stucsie/stu-online-judge

* 'master' of github.com:stucsie/stu-online-judge:
  Modify end_at type error for ExamPaper model
  Add ExamPager model
  Model ExamProblem set fraction default 0
  add model ExamProblem
  修改Appendix Model 關聯名稱 problem_id -> problem, array() -> []