Make the gem's build more sane in RVM environments

Resetting of RVM environment to allow each of the examples and integration tests to have their own environment should work now.

Added Sauce public job links to OutlineTable::ExampleRow's, to go along with @imurchie's changes (eg in https://github.com/saucelabs/sauce_ruby/commit/e78aa66c2f7447cb93264f6e5004db2d25f38bc7).

Prevented Sauce job links from being added to RSpec environment, if the user isn't using RSpec.

Improved stability of Cucumber integration tests by specifying Sauce browsers rather then relying on stub or defaults.