There might be answers to questions without values,
those would have hit the exception. So it is better
to just ignore those questions.

Conflicts:
	src/main/java/de/thm/arsnova/controller/SessionController.java
	src/main/java/de/thm/arsnova/dao/CouchDBDao.java
	src/main/java/de/thm/arsnova/dao/IDatabaseDao.java
	src/main/java/de/thm/arsnova/services/ISessionService.java
	src/test/java/de/thm/arsnova/dao/StubDatabaseDao.java

Conflicts:
	pom.xml
	src/main/java/de/thm/arsnova/controller/SessionController.java
	src/main/resources/log4j-dev.properties

The resource by default now includes the total stats. A user parameter
has been added to request user specific data.

This change intends to restore compatibility with ARSnova Overlay.

This change also removes the "lockSession" method from CouchDB.
Instead, the more general update method is used which also
has the required caching annotations.

Note that due to the way it is currently implemented,
we have to clear the whole cache once a set of
questions published or unpublished in bulk.

Changing the Session object the way it was done previously
interferes with the new caching mechanism. The objects are
now long-lived so any direct changes to it which are not
in the spirit of its use case have to be removed. In this
case, changing the creator information invalidated many
of the isCreator checks sprinkled through the code, as
the new creator's name would have been the string
"not visible to you."

A NotFoundException was mistakenly thrown when the Session was set to
null via Socket.IO. Additionally, the user count was sent before it
had been updated.

Closes GH-13.

Added few pp Attributes to SessionInfo. Requests for Public Pool Sessions now return SessionInfo instead of Session.

Closes GH-12.