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. 
It looks like this is a target for a synthetic click to get focus in the right place, is that right? If so, .focus() might work better than .click(). And you should comment both here and in the JS that focuses here to make clear what's up.