ENH: use faster, GPU-compatible random number generator
HACK: put encoders and decoders into shared vars

- makes graph analysis easier later
Learning with test_learning works
Print statements removed from hPES

- #14 base case addressed by this and previous commit
Update to ensure docs generate.

Since theano is tough to get running on readthedocs,
it's easier to just mock out theano stuff that we use.
Added some mocks for the new theano random number generator.
Ensemble update handles case w/ no decoded_input

- if X hasattr('type') then there was decoded_input
  otherwise don't bother recalculating J
- fixes case where no decoded_input is given
Merge branch 'master' of https://github.com/ctn-waterloo/nef-py
Added basic cache for inv(Gamma) and A.  Upsilon is still computed each time (as in Nengo itself) First pass at implementing Issue #2
Removed debugging message
test_enc.py - Added timing code to build process and simulation process (for benchmarking).