Manual delete cleanup details

proposal for e/management#951

update system persistent info stored on the following files :

• /mnt/repo-base/volumes/accounts/auth.file.done
• /mnt/repo-base/volumes/accounts/auth.file

when using manual account removal script : scripts/delete-account.sh

script input uses : user@e.email

• strip @e.email suffix to get mbox account name
• find the line on auth.file.done and verify there's only one line concerned
• from this line, get the external email used to register
• delete all lines in auth.file refering to this external mail address