Filter unwanted/inappropriate websites

Moved from #13.

Some of the modules have a possibility of generating traffic that could be harmful if not outright incriminating. Without some kind of "safe mode", users could be putting themselves at real risk.

Possible methods:
- Filter by profanity in URL and other descriptors.
- Use already safe methods like Google Safe search.
- Filter by top-level domains (.org, .gov, .tech tend to be safer bets)

This could have the effect of making traffic less believable, any making any real "unsafe" traffic stand out more. This should certainly not be the default.