Removed additional filters from modules view. Fixes issue #3369

#### Steps to reproduce the issue

Go to:
- Extensions -> Module Manager

You will notice that there are two filters for filtering between "Site and Administrator". And both do the same task.

![filters](https://f.cloud.github.com/assets/1375475/2512543/79017414-b427-11e3-87d1-55cd6d52ce1b.png)