rafter overall system test eqc stub
more next_state functionality for system test
add some postconditions to system eqc_statem test
build up a leader state and add invariants to system test
Track a model command index in system eqc test

Compare the model commit index to the real commit index in
rafter_system_test_eqc.erl
stop node with low frequency in system test
dont call stop_node with empty list in system test
WIP
passing system eqc test
fix config eqc test failures due to api changes
Merge pull request #4 from andrewjstone/moar-eqc

Moar eqc