Fixes removing placeholder after paste

A small bug fix for removing a placeholder after pasting new text to an empty editor.

Now when you paste text to an empty editor, a placeholder stays in place and blur/keypress event is needed for the placeholder to disappear.

![screen shot 2013-12-04 at 10 55 48](https://f.cloud.github.com/assets/312938/1672041/4e24acac-5cca-11e3-9f78-c2f9979b4868.png)