Allow generation of unminified CSS file

[treyhunner]

I am switching to django-tailwind-cli from an npm-managed version of Tailwind and I'd like to keep using the unminified CSS file I generated before, as I sometimes like to scroll through the diff and ensure sensible classes were generated (I minify later on in my asset pipeline).

This would:

• Add a TAILWIND_CLI_AUTOMATIC_MINIFY setting that can be set to False to disable minification
• Add a --minify and --no-minify flag to override that setting

I am open to alternate names if you feel TAILWIND_CLI_AUTOMATIC_MINIFY is too verbose or alternate implementations (like allowing --no-minify but not allowing customization via a setting).

[oliverandrich]

This is a good addition and a great idea. I looked into the pull request and merged it. I expect to release it on the weekend in a new version. I have to make up my mind, if I want to merge another feature into the release or not.

Thanks for the contribution.