Function adding

```
First I want to show my appreciation to the author.The app is excellent and
useful when I want to block some sick ADs in other apps.
But what I installed from some stores before I visit this project homepage was
the fack app.It pushs AD every time I connect my device to the Internet.It's so
despicable to add ADs to other one's app whose source code is explosed to the
public.
So I hope that you can add the function to this app that it can block some ad
providers which can be seen often.
Thanks!
```

Original issue reported on code.google.com by `ibmp...@gmail.com` on 24 Jan 2013 at 4:07

The issue requests blocking frequently seen ad providers but names no files, tests, or entry points. First clarify which providers and blocking behavior are required, then locate the app's existing filtering code and define tests that demonstrate the requested behavior. Done means the specified providers are blocked without breaking other network access.

Written by the indexing model from the issue text.