* First cut of supporting quantiles ("percent ranks") per allele. Closes #87.
* Some refactoring of amino_acid.py

This builds on #114

Implement BLOSUM62 encoding

* Switch from JSON to YAML for hyperparameters
* Pin tensorflow (hoping will help with #110)

Fixing code typo: allelle -> allele.

update setup.py

Remove versioneer

Set up versioneer

Fixes #47.

update README

Add speed test script

Reuse Keras models optimization

This should give a substantial prediction speed improvement as identified by @rohanpai

* Add borrow_cached_network() method to Class1NeuralNetwork
* Use cached models at in Class1NeuralNetwork.predict
* Set names for all neural network layers so the model JSON is identical for identical architectures

Change ensemble size from 8 to 12

Bump keras version, set mhcflurry version to 0.9.1