Django-letsencrypt

- Bump YEAR in LICENSE
- Rework some of the wording in the `README.rst`
- Added `English` as a `Natural Language` `classifier`
- Internal Changes
- Added a simple version manager script
- Added version check to `make test`
- Bump `travis` tests for `1.10.4` to `1.10.5`

- Python 3.6 support

- The `challenge` field has been made `unique` on `AcmeChallenge`
objects
- Migrations added to this release
- A data migration will remove duplicate challenges in this release.
As with any Django migration, be sure to backup your database first.
- Fixed issues:
- [GH-2](https://github.com/urda/django-letsencrypt/issues/2)
- [GH-4](https://github.com/urda/django-letsencrypt/issues/4)

- Migrations added to this release
- **This means v1.0.0 WILL NOT WORK. Use this version instead!**

- Production ready model, admin interface, and app usage is released.

- Made some minor fixes to the `README` file to work on Pypi