Remove Saucelabs

[tbranyen]

While its nice to test real browsers continuously, this service absolutely sucks.

It does not:

• Have stable and consistent runners which means false failures
• Allow contributors to run tests in their PRs causing false failures
• The interface on the site is terrible and the new beta is even worse

/rant

[samccone]

Ref https://github.com/travis-ci/travis-build/pull/356#issuecomment-124078458