Make all tooltip text align to the left by default
ngCkEditor directive: Make it possible to delay initialization of ckeditor until a specified event occurs

This is used as a workaround for this bug in ckeditor:

http://dev.ckeditor.com/ticket/11789

The Supplemental Information field (forthcoming) is within the settings panel of each question, which is initially hidden. Therefore, we need to wait until the settings panel gets shown before attempting to initialize any ckeditor instances within it.
Edit Quiz: Adjust spacing of control labels
Edit Quiz: Add the Supplemental Information field

Note: This is implemented for Edit Quiz only at this point - i.e., the field is saved, but it doesn't get displayed when taking the quiz.

The Supplemental Information field is intended to show additional information to the user after they submit an answer. It gets shown regardless of whether or not the submission was correct.
Add flexbox.less as a dependency

Add it to styles.less to enable using the flexbox mixins throughout the project
Add a hasClass helper method for testing whether an element has a particular class in Protractor

Slight refactoring in the quiz editor specs to use the helper method
Take Quiz: Put the Next button inside the submission result box

This makes the placement more consistent. It's also a bit more strategic, since if the submission is wrong, the Next button appears next to (or underneath) the correct answer and explanation, which increases the likelihood that the user will actually read it, instead of skipping over it.

Also, this removes having to have multiple instances of the Next button physically present in the DOM, which made writing tests a bit tricky to make sure we were finding the right one to click. (There are still multiple instances of the Submit button, however).

Finally, I'm using the flexbox for layout within the submission result box, which greatly simplifies things.
Make the Take Quiz e2e tests more flexible

The sample quiz that's used for the Take Quiz e2e tests has been moved into a separate JSON file. The e2e prep script (prepare.js) uses it, and takeQuiz.spec.js now also loads it in and uses it. Added some helper methods to submit the current question either correctly or incorrectly.

There should now be far fewer things to update if I add questions to the sample quiz. When testing something specific, such as whether the alternative answers are correctly accepted for fill-in questions, I still use hardcoded values for clarity, but for general things like quiz navigation, I'm now using the helpers.
Take Quiz: Show supplemental info after question submission
Temporarily remove node_nodules from gitignore to fix an issue with deploying to heroku