tagging dev-only code (@remove-on-publish-begin/end) and pre-eject-only code (@remove-on-eject-begin/end) #257 (#257)

Fixes #532

* Update Jest

* Remove default snapshot test

* Fix a few things

* Add a simple default test

* App.spec.js -> App.test.js

* Fix e2e test

* Bump Jest

Disable timer mocking and enable verbose output.

Fixes #186

The problem has since been fixed upstream.

This reverts commit f7011e04.

This fixes #302 by temporarily forking `detect-port`.
Hopefully this fix will be merged into the original project, and we can refer to it again.

Also fixes #194

* explicitly specify ESLint config path for editor plugins

* changed to use single quote

Related to #72, c2ba7a4a

* dogfood eslint config

* moved linting to e2e

Fixes #38

It is easier to add more scripts later this way.

* Make errors and warnings nicer

* Fix license stripping to not be eager

* Minor tweaks

* Use a custom eslint rule list

* Sort rules

* Relax some rules