Update change notes with release date.

Prep 2.0.14 release

Update RELEASING.txt

- Merge `tox -e lint` description into `tox -r` command description
- Use $TOX as an environment variable command

Merge pull request #458 from stevepiercy/2.0-branch

Backport #226

There is no trove classifier for PyPy3

Prepare 2.0.10 release

Prepare 2.0.9 release

Tagging 2.0.8

Tagging 2.0.7

Tagging 2.0.6