Feature/issue 165

Adds functionality that allows the user to whitelist certain potential trackers which need to be whitelisted to work. E.G. Youtube comments. This feature is already present in the chrome version but this would add it to the firefox version. CC @jsha for review. 
This file should actually be deleted since we don't use it any more (the CSS is included inline). But to answer your question, the !important flags are included because, at least in chrome, my css was being overwritten by page specific CSS even though my css is pretty tightly scoped. Rather than looking into why this was happening I added the !important directive, which seemed to fix the problem. This is probably not necessary in firefox since inline css always takes precedence.