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

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

caused in past server errors

* rename methods to clearify that this are sockets

If a session key was used in URI path which dous not exist,
send HTTP NotFound to client instead if running into NullPointerException.

This is a quick fix for HTTP session timeout which will result in some
strange behavior in client devices.

THIS MUST BE REVOVED if client JS code is able to re-authenticate from
local storage after session timeout.