Added test_simplenode.py test.
seed the random number generator in test_simplenode
add concurrency support to simplenode

- ref #61
- add a run method to simplenode
- origins tick to pass output in messages
Resolved merge conflicts.
Merge branch 'simplenode-support' of github.com:Hudon/spike
Added synchronization for exit of inputs.
remove self.inputs array and make all Processes consistent

- Other non-EnsembleProcess processes were not finishing the same way which
  forced us to handle them seperatly (self.inputs). This is now fixed.
Merge pull request #77 from Hudon/input-exit-sync

Added synchronization for exit of inputs + James' normalization of synchronization.
Merge remote-tracking branch 'origin/master' into feature-sub-ensembles
replicate the probe FIN/ACK sequence in AggregatorProbe

- when probes are done, they send a FIN to the Aggregator
- Aggregator used to not consider this FIN nor the fin that it has to send to the Network