add type of user account
adjust test for new user account type
UserServiceTest which test persistence of the maps

This provides smaller and cleaner Interfaces for each context.

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.

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.

questions object

This patch uses AbstractController class to add exception handlers
into controllers. These handlers are used to detect some runtime exceptions
which can be thrown in any layer e.g. DAO or service layer.
They recognize NotFoundException and ForbiddenException. Test classes are
able to check if any of these exceptions are thrown during runtime.

/getSkillQuestions/{sessionkey}, by default sort by subject but if
getSkillQuestions/{sessionkey}?sort=text the result will be sorted by
subject and text

doesnt throw exceptions if fields are not set. remove info output

If a session was not found in database this will result in http 404,
if the session is not accessable for the current user the request will
result in http 403.

The old behavior was to check for null. This was the response if the
session was not found or the current user could not access this session
(not owner and inactive sessions). Both ended up with http 404 - not found.

The URI to be used contains the session id the question is linked to. If
the resulting question object did not match the given session id an error
HTTP - NOT FOUND will be send. This will also be done if no question was
found.

This layer can be used to create a StubDAO for use with unit tests.

* @ResponseBody Annotation for JSON Response
* Old ARSnova Servlet does nothing
* New Spring Servlet loads Beans, Services, Security and SocketServer
* One Property Loader which is used in XML Spring Configuration and with
@Value Annotation

cleanup is now working as expected

* If a user posts new feedback, while having already posted one, the value
gets updated. This prevents feedback adding up.
* If feedback is too old (10 minutes), it gets removed. For testing
purposes the cleaning routine currently runs every few seconds, and
feedback only lasts a few seconds as well.
* The deleted feedback changes are broadcasted to:
	o All users, if feedback of other users has been deleted.
	o The user whose feedback got deleted.

Currently, this is a huge mess! There are three types of "Session Ids":
* The Socket.IO "session"
* The internal CouchDB session id
* The ARSnova session keyword

A severe clean up is needed before proceeding any further...

remove websocketcontroller and let sessioncontroller do the
authorization
add toString to User entity

Properties from properties file are available in all beans now.
CouchDB connection in SessionService will be created using these settings.
If a connection fails, the next request will have a new try instead of
throwing an exception.

This method uses transaction level READ_COMMITTED.