Delete election data

[Cryptosaurus]

Is there a way to delete an election and all the associated data after it has served it's purpose?

In particular, election data includes names and email addresses which are personal data, and it is good practice to delete such data when not needed anymore.

There's been some work done in the past on deleting an election with #161 but it seems that it has not been merged in the main branch. Also that proposal seems to "hide" the election rather than really delete it, since it includes an undelete functionality.

[benadida]

this will be fixed by #456