初始化mongodb实例
Merge branch 'master' of https://github.com/gutan/189Calendar.git

Conflicts:
	calendar/src/main/java/com/cn21/app/calendar/dao/MongoDBClient.java
	calendar/src/main/java/com/cn21/app/calendar/service/impl/CalendarServiceImpl.java
	calendar/src/main/java/com/cn21/app/calendar/utils/PropertiesLoader.java