Update client.js to no longer need the html bridge if flash doesn't exis...

I ran into a bug where hovering over an element in a browser without flash would cause a javascript error when it tried to reposition the non-existant bridge.

It's happening because we glue() the bridge when we create the singleton, but do that before flash is detected. If flash doesn't exist, mouseover events still fire.

Here's a fix that destroy()s ZeroClipboard if detectFlash doesn't exist.