Mixed content blocker fixed

I have now fixed the mixed content blocker issue. I will do some more test but otherwise it looks very good. Throwed some stupid code out and the resulting blocker is just 10 lines of code.
Lesson of the day: always remember KISS princible ...

Christmas is almost here and I would like to kick 1.5.5 out sooner than later so that I can start encrypted edition.
So there isn't much in new version but those few are important things.

Included in 1.5.5:
- Fixed mixed content blocker
- Optional tracker blocker list which contains 35 000 blocker rules (there is just no way I can finish cleaning this list before Christmas so that's why it's optional) and a way to change your default list from Tracker blocker tab.
- Fix all the cookie things I told in previous blog post.
- Maybe (if time left) add file information to Downloads tab
- Upgrade Qt 5.1.0 to 5.2.0
- And enable random proxy feature back again

That's the plan.