call show on cloned node AFTER inserting it into DOM.

I'm using mediaelement in an embedded IEFrame, and it has some behavior in ie10 and ie11 that is not different than in a normal browser.

It looks as though ie is still reverting to using flash for mp3 playback.  When calling remove on the player, the function erred out at this line (giving a Permission Denied error):
```
t.$node.clone().show().insertBefore(t.container);
```

Calling show() after inserting the newly clones node into the DOM avoids that error, and the remove function completes as expected.