Prevent user passwords showing in error emails

Use the sensitive_post_parameters decorator to redact user passwords
when an error occurs in the token view.
Revert "Prevent user passwords showing in error emails"

This reverts commit 2ad939218b4b70703f15ac600c7a4bea909fe219.
Prevent user passwords showing in error emails

Use the sensitive_post_parameters decorator to redact user passwords
when an error occurs in the token view.
Merge pull request #169 from FreakyDug/redact_password

Prevent user passwords showing in error emails