Fix double moderation dialog

registerInitFunction will be triggered when flow is loaded, and when making
certain changes in DOM (e.g. adding a post, which would need some controls
bound)

tipsy needs us to bind events outside of a (post|topic|...) container
because it will add dialogs at the bottom of HTML. Anything inside this
registerInitFunction will be executed again when, e.g. a new post is added.

This causes multiple click-binds on document, so clicking a moderation
button can lead to multiple moderation dialogs being fired.

As a quick fix, I'm adding a data-attribute to signify the event has already
been bound, and not bind again if that's the case.

A more proper solution should be worked on, but work on refactoring much of
the JS is already on its way.

Change-Id: Ib9a8d7f67a1006c9ae99a1fe3a42dd11777798c7
Merge "Fix double moderation dialog"