color pytest's outputs to improve readability

[Borda]

before:

after:

cc: @sirosen @edgarrmondragon

[sirosen]

This is CI specific, isn't it? I get colors just fine in local usage.

This is fine, although I wish there were a more elegant way of telling pytest to colorize when in CI.

All that aside, thanks for the contribution! Merging. 😄

[Borda]

This is CI specific, isn't it? I get colors just fine in local usage.

this is for any pytest run, but if you have some other personal/global configuration you could see colors locally already... I was not :)

[sirosen]

It could be related to your tox version as well. There are a few layers I could imagine having impact (platform, terminal emulator, pytest version, tox version, even the python version which impacts dependency resolution...)