Resolve email address to user FQN during task assignment.

When a task is assigned to an email address, the current behavior is to use the user portion of the email address to assign the task and strip the @ sign and domain. This causes an issue when the username and the email address are different. The only way to work around this currently is to take the email address and input it into a SmartObject that returns the correct username or FQN. The task recipient field should accept the user's email address and automatically resolve it to the correct username.