Add UserIdentityCardNumberController

Basic mechanics for updating a User’s identity_card_number
Add form for editing User#identity_card_number
Override _show_user_info to include ID Number
Override _signup to include ID Number
Redact User Identity Card Numbers

When a User record is saved, create a CensorRule that redacts the
identity_card_number attribute if an appropriate CensorRule belonging to the
user does not already exist.

Uses class_eval rather than instance_eval to enable the definition of
the update_censor_rules callback method.
Include Name and ID Number in Initial Request email
Add integration specs for identity card number

Covers:

  - Signing up with identity card number
  - Changing identity card number