Add option to disable autoprefixer in CLI

[adamwathan]

There are a lot of situations where people are using tailwind build to avoid ejecting from things like create-react-app or whatever the hell Angular people use. Those tools already run autoprefixer though, so running it twice just slows things down for no reason.

This PR adds a --no-autoprefixer option to the build command so people can opt-out of it for better performance if they are already prefixing their CSS in a later step.

@MattStypa: Would appreciate your eyes on this if you have a minute 👍

[MattStypa]

@adamwathan Looks good. 👍

At some point in the near feature, I want to take a stab at refactoring the build command. The argument based configuration approach for build functions is unsustainable.

[adamwathan]

The argument based configuration approach for build functions is unsustainable.

Yep agreed 👍 Cool thanks!