Test release versions for python 3.5 & 3.6

[dhimmel]

I'd like to look into the failing builds for 3.5 and 3.6, so this PR is currently just a stub

[coveralls]

Coverage remained the same at 87.361% when pulling 2c03541 on dhimmel:patch-1 into a41db86 on Grokzen:master.

[dhimmel]

I'd like to look into the failing builds for 3.5 and 3.6, so this PR is currently just a stub

The error I was talking about was here:

E           TypeError: Unexpected keyword arguments passed to pytest.raises: msg

which has also been reported here where a solution was to change msg to message. Here's raises in the pytest source code if that's helpful.

Nighly is currently failing, I believe to the following from the Travis docs:

Recent Python development branches require OpenSSL 1.0.2+. As this library is not available for Trusty, 3.7-dev, 3.8-dev, and nightly do not work (or use outdated archive).

However, rest of the tests are passing now.

[Grokzen]

This is already implemented/fixed in master branch, so closing this MR