Example transmits sin rather than constant value.
Add requirements.txt, modify docs conf accordingly.

Pull in Nengo using Git, modify when a Pip release is made.
Correction to requirements.txt
Update requirements.txt
Update requirements.txt
Update requirements.txt

Include bitarray.
flake8 and documentation for simulator.
Further documentation on Nodes.
Merge branch 'master' into f-of-t-nodes

Conflicts:
	nengo_spinnaker/simulator.py