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

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

 - 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

Retrieved @Cacheable and changed updateSession method in SessionService, now getting the session by keyword and set all fields that may have changed to a new value

Removed @Chacheable from getSession function, because the Update of a session wont work if only the cache is used for loading the content of a session

Requesting partial lists would interfere with Spring caching so
pagination is handled by the newly introduced PaginationListDecorator
in the controllers. This additionally allows to determine the total
count of items (independent from pagination parameters) which is not
possible with CouchDB.

Added TODOs to keep track of methods still evicting the whole answers
cache for future improvements. Additional refactoring is necessary to
implement these.

Direct method calls bypass the caching proxy if AspectJ weaving is not
configured.