1.Add GroupAuthenticaion.interceptor. 2.Add ShowOneTask.action.
Merge branch 'dev' of http://git.net9.org/mored/tyche-online-judge-system into dev

Conflicts:
	web/WEB-INF/src/com/tyche/group/action/StatusAction.java
	web/WEB-INF/struts.xml
1.add ShowGroup.action show Task.action.
1.change model's int to Integer. might cause problem
2.move json authentication to user.service.
add ace editor to Problem.html
removed rapidjson from thirdparty
fixed some typos in servlet and implemented htmls
basic frontend framework & improved LoginAction
implemented notification in Group
rewrite LOGIN result
reorganized existing codes
finished reorganizing existing codes in Group
finished reorganizing existing codes in Group#2
finished reorganizing existing codes in almost all packages
bugfix for reorganized codes
1.Finish userService and Problem.action
bugfix in ShowProblemAction
prevent user from logging in multiple times
removed unnecessary jsp
notifications in grouplist