server(): not necessary
rafter_system_test: enrich model state

model state includes list of nodes as well as vstruct generator instead
of just the resulting vstruct for 'running', 'old' and 'new' vstructs
voting: use dict instead of orddict
removed dirty hack
move logdir to /tmp to avoid hard disk writes
give rafter_system_test 5 minutes to run
go to only up to around 20 nodes