Add minimum coverage requirement for pytest

[jacebrowning]

@joshfriend what do you think?

[joshfriend]

@jacebrowning I like it 👍

[jacebrowning]

@joshfriend adding additional verbose flags will make the lines much longer. Still want them?

[joshfriend]

I guess since pytest doesnt use the test docstrings in the output like nose does, verbose really doesn't do much. If line length concerns you, use -m instead of --show-missing when running coverage

[jacebrowning]

@joshfriend so is this change good as-is?

[joshfriend]

yes