Global Settings; Auditing always shows changes to encrypted data

When saving Global Settings non-blank encrypted properties are always audited. This occurs because encrypted data is randomly changed, and therefore generates a different value so is always changing.

The following properties are affected:

+ GL External User Password + Proxy Server Password + Address Database Password + Email Smtp Password + SMS Password (old interface) + PPSR NZ Consumer Secret (will likely be removed before version 4 is released) + PPSR NZ Subscriber Key (for new MBIE API)