Network example

Resolves numenta/nupic.core#154

Adds the example `examples/network/network_api_demo.py` that computes identical anomaly scores to `examples/opf/clients/hotgym/anomaly/hotgym_anomaly.py` but using the Network API directly instead of the CLAModel and OPF.
@rhyolight - a bit of confusion as I certainly was not advocating for randomly misaligning the comments. My rationale was in advocating for the committed version (always indent two spaces) - see the link below. Also, I support your suggestion for not doing inline comments to avoid the issue in this particular case.

https://github.com/numenta/nupic/blob/70b04e46ae18faf20d58f0b707b5b8a7204aade2/examples/network/network_api_demo.py#L34-L35

Similarly, I really don't think we should align things in doc strings. The link below is a good example where someone tried to do that. Now if you add a new param that is longer than the others, you have to update all the others, which seems prohibitively painful to me. Not to mention that indenting all the lines so much results in the doc string taking up a ton of lines.

https://github.com/numenta/nupic/blob/70b04e46ae18faf20d58f0b707b5b8a7204aade2/nupic/research/spatial_pooler.py#L73-L193

If you want to discuss more let's do it when you're in the office.