The new NoContentException should indicate, that there is no error, but
the server could not provide a response object. This will result in
HTTP Code 204 - NO CONTENT => see RFC2616

Fixed two NullPointerExceptions wich might occure in QuestionService or
by using CouchDBDao from QuestionService.

This change is needed due to client developer restriction not to round
returned value on client side but on server side, because this would
change sth.

This change is needed due tu websocket security issues.

Method SessionService::broadcastFeedbackChanges is obsolete since this
method is used in FeedbackService.

FeedbackService::broadcastFeedbackChanges must not be annotated with
"@Authenticated" since authentication is not implemented for web sockets.

Added menu for "Documentation" containing a list of dependencies, a small
indroduction how to install ARSnova for development usage and a link
to generated API docs.

This provides smaller and cleaner Interfaces for each context.

cthelen recently

remove methods from session controller which are now in its own
controller

All relevant information about users (e.g. session mebership) are
accessible via UserService.
The method IUserService::getCurrentUser provides information about
the actual logged in user. If no user is logged in, this method will
throw a UnauthorizedException which will end up in 401 HTTP error.

This adds URI
"/session/mysessions"
in addition to the old URI which still can be used.

All feedback methods are available in class FeedbackController, all
question methods are available in class QuestionController.

None of the URIs are changed!

Added second URI for method QuestionController::getSkillQuestions that
matches common URI rules in ARSnova:
"/session/{sessionkey}/skillquestions"
Both, the old an the new URI can be used equally.

Currently, there is an issue with the response. It seems like Spring
is trying to resolve some view, but fails, and then displaying
a message stating POST is not allowed.

If some kinds of feedback values do not exist do not throw the exception
NotFoundException. This only indicates, that these values should be '0'
which is the default value.

NotFoundException should only be thrown if the requested session of
feedback does not exist.
Every session has a feedback - sometimes with only 0 values.