Fixes to play nicer with remix again

The paste button was hidden in the toolbar, because the old ui would hide and show that button. Now it simply disables.

The paste button now flashes as it does in gh-book. I think the styling of the button needs more love.

Math popover is a little wider than it used to be. This is because adding the Copy button used up the remainder of the space and now the cheatsheet option no longer fits, it pushes the Copy button down.

Finally, there is also a fix in Aloha to make this play well with chrome version detection. There is a version hack in gh-book that can be removed after this. And remix can upgrade to jquery 1.8, which is needed to make the paste plugin work properly (bug in jQuery.has()).