Python support update

[sgaist]

This merge request updates the minimal Python version to 3.7 and adds 3.8.

It also adds the tools required to run the tests to list of dependencies.

Fixes #5

[coveralls]

Coverage increased (+0.09%) to 94.966% when pulling bde42a6 on sgaist:python_support_update into 2b3f8b5 on morepath:master.

[jugmac00]

LGTM - with some comments. Please try to apply the suggested changes.

[jugmac00]

Hi @sgaist

currently, CI is broken, see https://travis-ci.org/github/morepath/more.webassets/builds/731987458

The reason seems that Travis nowadays need the "matrix" syntax for configuring several Python interpreters, also see here
morepath/morepath_cerebral_todomvc@c5b4137

As a side note .. I just saw you force-pushed some new changes. While this works, there is one problem with this. Above I added some inline annotations on what needs to be done for this pr - as you force pushed a new state, these do not match any more. On the other hand, if you just added another commit, I could easily see if you applied the requested changes. Do not worry about too many commits, as the maintainer always can squash all changes into one commit on merging.

So, the rule of thumb I follow - when I work together with other people, especially via GitHub, I do not force push.

Thanks for contributing!

[sgaist]

@jugmac00 I see your point, and I will do it like that.

I forced push because I am used to provide sets of commits (even if squashed) that are "clean" in the sense that the kind of small fixes you asked were better served by being integrated in the original work.

[jugmac00]

@jugmac00 I see your point, and I will do it like that.

I forced push because I am used to provide sets of commits (even if squashed) that are "clean" in the sense that the kind of small fixes you asked were better served by being integrated in the original work.

I absolutely noticed that your commits are super clean! 👍

[jugmac00]

One last thing - could you please add a change log entry? Thank you!

[jugmac00]

Thank you!