converted communication example to ipython
minor cleanup to communication example
Created controlled oscillator examples
Split steps to have adding probes a separate step
added combining notebook
less verbose 2drep and controlled integrator
Add helper for piecewise inputs

Progress towards issue #116
Update controlled oscillator for piecewise
Fixing typo in objects.py
Added noise to least square decoder solver

- Fixes the failing test_product
- Also added a helper to plot tuning curves,
  needs to be refactored a bit though
Simplified connections with simulator ops

- Created a new ProdUpdate operation
- Made DecodedConnection and DecodedNeuronConnection subclasses of
  SignalConnection, and renamed DecodedConnection to
  NonlinearityConnection
added integrator example
added a spike probe

call this with, e.g. model.probe('A.spikes')
then you have data=sim.data('A.spikes')
updated the many neurons notebook
standardizing notebooks and notebook naming
Merge branch 'master' of https://github.com/ctn-waterloo/nengo into peter-examples
Updated spike probe with new connection types
Fixing typo in helpers.py
Add white noise signal generator

- Small connection change as well
Converted addition example to ipython