Add tags to repository and include and LICENSE into sdist

[nicoddemus]

Hi,

Please push the tags of the releases to the repository, it helps maintainers of packages of other distributions. In the same vain, please include the LICENSE file into the sdist.

[toddrme2178]

Seconded. Both are very helpful, particularly having the LICENSE file in the source archive.

[edziegle]

I'll third having the LICENSE available!

[gaborbernat]

Development moved to https://github.com/pytest-dev/pytest-env