User was able to click delete button multiple time which could cause
multiple delete requests. This commit disables and hides the delete
message button after the first click and shows a spinner until http
the delete request responds.
Also adds a casperjs test to ensure that spinner becomes visible and
delete button becomes invisible after clicking on delete button for
first time and hides spinner and show delete buttton when message is
deleted.
Fixes: #11219.
This should make it easier to find the templates that are actually
part of the core webapp, instead of having them all mixed together
with the portico pages.
Mohit Gupta
Tim Abbott