Include audited_changes attribute in the audit trail

We need to add the content of audited_changes to the audit trail printed to STDOUT when audits_to_stdout feature is enabled. Instead of only printing the names of the fields that have been modified, audit trails related to creation and update of audited models should be printed to logs including the values of the attributes that actually changed.

Sensitive data such as passwords, app_keys, client secrets, user_keys must be obfuscated.