fix(capitalize test): Create a working test for the capitalize directive

* Replaces the default test (which would fail) with a working check that an
  input field bound to an ng-model will have it's value capitalized.

BREAKING CHANGE: Moves the check for SauceLabs credentials in karma.conf.js
  to run in Travis only
minor(capitalize test): Improve The Flexibility of the capitalize Test

* Expect the value to be whatever `scope.text.toUpperCase` should be.
* To change the test text, only the value of scope.text needs to be changed,
  and not the assertion.