Merge pull request #516 from NicoleRauch/master

Turned member nickname in administration/memberTable into a link to memb...
small layout change for gdcr
First draft of new waitinglist feature.
First tests for waitinglistEntry and persistence.
Introduced waitinglistAPI and tests for it.
Improved tests for the waitinglist object.
Now the subscription to an activity checks whether the prospective registrant is on the waiting list and is allowed to register.
Added tests for subscription off of waiting list.
The database object needs to be wrapped into a WaitinglistEntry object.