Add option to add and remove blocked hostnames via query string

[kpence]

I find this incredibly useful personally. What do you think about adding a feature like this?

The point is that you can add and remove hostnames via query parameters like this:

moz-extension://<uniqude id>/data/options/index.html?add=youtube.com
moz-extension://<uniqude id>/data/options/index.html?remove=youtube.com