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 here are the two references for my change. First, PEP 8 says to very rarely use inline comments but if you do then use at least two spaces:
http://legacy.python.org/dev/peps/pep-0008/#inline-comments

Also in PEP 8 it says not to use whitespace to align operators and I think this is good justification for not aligning comments for different statements:
http://legacy.python.org/dev/peps/pep-0008/#pet-peeves