Load blacklist from an external URL

[tkorakas]

AdBlock loads blacklists from an external URL. I think this make "deploy" process faster and easier. You could use something like Firebase hosting (free up to 5GB) to store the blacklist.

#73 on settings page you could let users to add their on blacklist URLs.

[keraf]

The blacklist is already loaded from the Github file of the master branch with a fallback to the local blacklist.