(https://github.com/thm-projects/arsnova-backend/wiki/Caching
^-- see List of cache entries and associated keys)

In some cases the Socket.IO servers used in test cases are not closed
when starting a new test. In this cases the tests will fail with
an address conflict because an other Socket.IO server is still running.

Using a new port, starting with previous defined port 1234 up to 1243 will
assign every new created Socket.IO server an other address/port.

An address conflict will still occure if an other service is running on
ports from 1234 to 1243, so it is generally a bad idea to have tests in the
hope that no side effects will occure from outside of application scope.

Conflicts:
	src/main/java/de/thm/arsnova/controller/LecturerQuestionController.java

fix bug where abstention questions are not exported

fix bug where not all attributes from grid questions are exported

implement: via two booleans you can now decide whether AnswerStatistics and FeedbackQuestions shall be exported, too

add empty test methods

add constructors to transport classes to parse "main"class

This fixes a potential NPE and should slightly improve performance.

See also:
003b064b

Also added documentation for the property.

 - add controller/service/entity/dao-functions
 - add motdlist so that users can tell the backend, which motds they have read
 - add admin account (in arsnova.properties: security.adminaccount).
 - add permission function for admin

Version information is now compiled as part of a build and written to
version.properties. It is exposed by the API.