[Interests] Improve detection of sensitive sites with Alexa

[marcosmenendez]

There are a few things that we can do to detect sensitive sites using Alexa categories. Maybe we have implemented them already, but wanted to make sure:

1. Update the list of sensitive categories (use column=discard) https://docs.google.com/spreadsheets/d/1h0pJhM4hjTQl2e7gDB58lw-1x-g_WGYtmd-3mDLbnsQ/
2. In case that Alexa reports multiples categories for a site, mark as sensitive (and delete) in case that any of them is sensitive
3. Let users mark a site as sensitive in their "your-data" page. If they do so, we should delete it from their database but keep it in another table so we can review them and decide if those domains should be marked as sensitive for any other user. By the way, this should be done as well with the queries