Remove unused entries

[niccokunzmann]

Once we have new entries, we may want to remove old entries.

Implementation ideas

• We can remove websites when they are unused for an amount of time.
• We can check automatically every hour if this domain is still in use
• We can just add a button so people can delete manually
  • deleting as well as adding may require an email address?

[niccokunzmann]

I think, deleting it after it could not be reached for a while is ok, assuming one does random tests every day and check about 30 times before removing it.