Media plugin option for hiding general tab

I had a case that I had to hide the General tab. The simplest way of doing that was to add one more option in media plugin. Disabling the Tab completely is not fusible, so I had to hide it.

![screen shot 2014-10-03 at 11 27 55](https://cloud.githubusercontent.com/assets/1997886/4504599/6eb42e4a-4ae8-11e4-978f-7ce12c1bfe41.png)

Please tell me your opinion on this solution and if you are happy with adding such an option, merge it. 

Cheers,
Alexandros
This one was asked by grunt but was missing