- `encode()`: Renamed to `int_to_base58()`.
- `decode()`: Renamed to `base58_to_int()`.
- Maintain aliases of old function names for backwards compatibility.
- Require node 6 at a minimum to support the newer ES features. Node
version functionality determined via https://node.green.
- Update dev dependencies to their latest versions. Mocha 3.4 relied
on a version of growl with a known vulnerability.
- Fix the keywords section, this field is actually an array.
- Update eslint syntax to ES6.