Testing improvements

* Some refactoring of the testing setup, dropping the globally required protractor, and run the test tasks with Grunt and a locally installed protractor. I added extra details in the README.
* Always run the tests on the production build.
* Use a shared config file for both `content` and `background` tests, and replace all hard-coded data with it.
* Get the extension ID dynamically, fixing the long standing issues with the hard-coded extension options page url.
* Fix the failing tests and make improvements where possible. All tests are passing now.
* Create a new quicktext for all the functionality tests in the `content` tests.
* Minimal testing for the pageAction popup, by opening the popup url directly.