Begin experimenting with integration tests
PARTIAL: Integrate Sauce Labs a little bit
Use TravisCI's tunnel when available
Re-organize variable definitions
Re-organize files
Only initialize test server once
Annotate Sauce Labs job with test status

This necessitates sharing a driver instances between tests.
Avoid browser bugs
Enable dynamic specification of browser
Define test script
Update package dependency
Provide Sauce Labes username to TravisCI

This allows TravisCI to set up secure tunnels to Sauce Labs before
`grunt` is invoked.
Extend data reported to Sauce Labs