Add manual member archive and expunge function. Reinstate with user login.

Archived members have records expunged and boolean set.

Switched MemberProfile.veggie to a NullBooleanField. This field doesn't do an awful lot so happy to change in dev and see what happens.

Progress

• Add archive, expunge and reinstate methods to MemberProfile.
• Add notice to MemberDetail that a user has been archived.
• Add button to MemberDetail to archive user, confirmation required. Similar to a delete view. Should we remove the delete view?
• Hide all archived users from MemberList views
• Reinstate user when they login and fill out DynamicUpdateForm again
• Reinstate user with button on MemberDetail

Later additions, for another MR

• Auto archive
• Notify via email, warnings and action taken