Autodetect a few different static site generators

[jasikpark]

Things that would be nice for the future (roughly ordered, see also #enhancements)

Try to autodetect a few common static site generators (hugo, jekyll, gatsby)

Maybe look into how netlify dev works... I'm sure it's probably just grabbing and running whatever's in netlify.toml?

[jasikpark]

https://github.com/netlify/cli/blob/master/docs/commands/dev.md#devexec

Probably a good ui, at the very least

[jasikpark]

aha! https://github.com/netlify/cli/tree/master/src/detectors

https://github.com/netlify/cli/blob/master/LICENSE (MIT)

[capnfabs]

Hey! Thanks for digging that up; it's a useful resource!

My current thinking is that the path to this would probably be:

• Have a --buildCmd option which allows you to specify the entire build command
• Support putting that + other options in a grouseconf.toml (which is something the arg parsing library supports for only a few lines of code).

This gets most of the way feature-wise; I'm still not sure that I want to have to maintain a bunch of detection logic, even if I can just port it from netlify 🤔

[capnfabs]

This is blocked on #6