Don't close dialog when dragging outside of it (take 2)

[mvandenburgh]

@manthey this line was what broke some dialog boxes -

dialogContainer.off('click');

When jQuery's .off method only receives one argument, it removes that event listener from the element it is called on and also all of its children. So what was happening was that line was removing the click event listeners from the buttons within the dialogs too. .off takes a second argument that lets you specify a specific selector to remove the event listener from. I've done that here -

dialogContainer.off('click', '#g-dialog-container');

So now it removes the click event listener from #g-dialog-container only, and not any of its children. I tested all of the dialogs I could find in the UI with this change, and it seems to work fine.

Fixes #140