Merge remote-tracking branch 'origin/master' into customization

Conflicts:
	src/main/java/de/thm/arsnova/dao/CouchDBDao.java
	src/main/java/de/thm/arsnova/dao/IDatabaseDao.java
	src/main/webapp/WEB-INF/spring/arsnova-servlet.xml
	src/test/java/de/thm/arsnova/dao/StubDatabaseDao.java
	src/test/resources/arsnova.properties.example