Email URI conversion fault

[zfi]

Cloud Session faults if a password reset request is made and the alternate email field in the user record is null.

[zfi]

The private function _convert_email_uri(email) attempts to search the provided email address for a '+' character and, if found, replace it with a string that is appropriate for a URI. It does not verify that the value passed in contains a string. This omission is addressed in PR# 46.