* cli: debug explanation for XVFB
* linting
* add chai-as-promised to CLI dev
* show Linux specific error solution if cannot verify
* add todo
* chore: consolidate github issue url logic
* linting
* add npm script lint-changed to quickly eslint fix changes JS files
* retry verify with our XVFB
* update errors and tests
* update CLI tests
* add test for display error message
* fix unit test
* add successful test with retry
* finish verify retry test
* warn users if hit display problem on first verify
* try to detect display problem when running electron and retry with our xvfb
* add warning message to spawn when attempting xvfb re-run
* add test for display retry behavior on spawn
* more comments for clarity
* fix typo
* Introduce CYPRESS_DOWNLOAD_BASE_URL to specify a base download url instead of download.cypress.io
* rename to CYPRESS_DOWNLOAD_MIRROR
* update spec_helper
* wip [skip ci] update
* wip [skip ci] update test
* [skip ci] fix env var
* bump sinon, create helper utility to always throw when a stub is called without being given stubbed behavior
* update failing specs
* fix some error messages
* update snapshot
* warning -> note, add snapshot tests
* change snapshot os.release, test env vars