Implement algorithm ranking service.
Merge branch 'master' of https://github.com/izeye/pilot

Conflicts:
	src/main/java/com/ctb/pilot/study/algorithm/controller/AlgorithmContestController.java
	src/main/java/com/ctb/pilot/study/algorithm/service/AlgorithmContestService.java
	src/main/java/com/ctb/pilot/study/algorithm/service/DefaultAlgorithmContestHistory.java