README not updated

[hu38]

it seems like the master branch now supports django version up to 1.10, but the readme file only indicated 1.4, which is misleading.

[timabbott]

The requirements list versions that are at least 1.4, not at most 1.4. 1.10 > 1.4, so I think the documentation is correct.

It probably would be reasonable to update the docs to cover that we support through 2.1.