[rbseverity] Fix the severity extension to properly support general comments

Review Request #9205 — Created Sept. 23, 2017 and submitted — Latest diff uploaded

rb-extension-pack, students

The severity of a problem was not being displayed on the review page, if
the severity was added using the add comment button on the review dialog

The drop downs menus for severity options on the edit review page
were not saving the model with the selected option. The model not saving
the selected option caused the data not be saved in the database when,
submitting the form.

The patch fixes the problem by saving the model anytime the severity
changes in the drop down. When the severity is saved it is properly added
to the database, and this fixes the problem on the review page.

I added a comment of each severity using the add comment button on the
reviewable page. On the review dialog page I added another comment with a
severity and published it from this page. I repeated the process adding
multiple comments with varying degrees of severity, and different
amounts of comments.

I ran the js tests with the extension enabled and all expected tests
passed. I had 2 failures, they seemed unrelated and other people were
experiencing them, and they are being filed separately.

All tickets had proper severity in the database and displayed it on the
reviewable page.