Switch to JSON Parser for SANS State

Switches to using the JSON library for parsing SANS state objects. This
provides numerous advantages:

- We do not need to maintain a custom (de)serializer
- JSON is a documented standard
- We can switch to type hinting in Python 3, currently a significant
amount of CPU time is spend reverifying typed params
- History becomes less brittle and will work from top level algorithms
- Allows new code to be written in a more Pythonic way (e.g. not forced
to use class level variables for them to be serialized)