Changed nnet.py to conform pep8
Removed nnet.py from whitelist, fixed #821
Fixed several more issues in nnet.py
Added reconstruction error to vae monitors.
Reconstruction error is mean squared error (mse), and is derived from theta, which is already computed by the monitor.
Reconstruction is mean from theta (not sampled).
Moved decoding sample shape in monitors from 3D to 2D.
Merge pull request #1276 from dmitriy-serdyuk/pep8nnet

Removed nnet.py from pep8 whitelist
Merge pull request #1274 from rdevon/vae

Added reconstruction error to vae monitors.