v3.0.0-rc.6

As the number of prereleases increases, so does the stability of roots v3! A bunch of changes in this one:

• Public API updated to be cleaner and more efficient
• Fixed a bug in which package.json files with no dependencies caused an error #421
• Added a setup function to extensions with which extensions can perform any async setup necessary
• CLI refactored, stabilized, and tested, docs updated
• roots watch --no-open will now not auto-open the browser
• roots clean now works
• roots new has seen a bunch of great updates with the next version of sprout

Look forward to another prerelease soon including bugfixes, an even more stable CLI, sprout namespacing, and more!