Merge branch 'nr/master-debug' into 'master'

Merge nr/master-debug into master

Added MaxPeerCountChurnGenerator. A churn model what follows a predefined "trace" that states how many nodes should be in the network. Nodes may be used for multiple times, thus overlays have to ensure to handle such events. The csv file must highlight the time when a churn should start, the length of the churn (used to calculate the inter arrival rate of nodes), and the number of nodes that is to be achieved. 

See merge request !26