Added .closest() to find Reply button on click; fixes #401

This is to fix the issue where the icon-comment icon is clicked in the
Reply button of a note; the icon is used as the target and incorrectly
assumed to be the button itself, which causes the reply form to spawn
inside the button.
Merge branch 'fix/notes_reply_click_issue401' into 'master'

Get Reply button as clicked target in notes.js.coffee

See issue #401

This is a small fix to properly find the reply button as the click target when an element inside the button is clicked (e.g. in this case, the ``<i class="icon-comment">`` element in the button, using the jQuery ``.closest(...)`` function.

Previously, the clicked element was assumed to be the button itself, which caused the comment form to spawn within the button when it was clicked (see the issue for screenshots & other details).