This prevents crashes caused by null pointers. Checks are moved to
the service class, and real objects are passed along.

QuestionByLecturerController.

class.

Excluded HttpRestApiTest from build process.

Strings. This fixes incorrect content types being set in the response
header.

Read, unread, and total count for interposed/feedback questions
implemented.

returned by some controller methods.

/canteen/foodvote => /canteen/menu/vote (GET)
/canteen/vote => /canteen/menu/vote (POST)
/canteen/foodvotecount => /canteen/menu/vote/count

/socketurl => /socket/url
/authorize => /socket/assign
Changed status code for /socket/assign to 204 (this does not create).

the header being present (e.g. with IE).

With this changeset the spring servlet configuration is separeted from the
application configuration. This will result in a main context and a servlet
context, holding only spring mvc information.

This change has a very nice side effekt: Spring AOP beans will be loaded
only once in application context, not a second time in mvc servlet context.

This patch should increase findbugs report and solve some issues that
will occure:

* Doing operation on NULL object
* Using wrong object type in hope of magic object casting ;-)

Conflicts:
	src/main/java/de/thm/arsnova/controller/QuestionController.java
	src/main/java/de/thm/arsnova/dao/IDatabaseDao.java
	src/main/java/de/thm/arsnova/services/QuestionService.java

Conflicts:
	src/main/java/de/thm/arsnova/controller/QuestionController.java
	src/main/java/de/thm/arsnova/dao/IDatabaseDao.java
	src/main/java/de/thm/arsnova/services/IQuestionService.java

and the users inside of it