Add Date to EmailComplexType

[burnalting]

Not all emails have a parseable Date timestamp, but it is the timestamp recorded of the email. We should have a Date String element within the EmailComplextType to represent accurately the Date timestamp recorded in an email.

[burnalting]

<xs:element name="Date" type="xs:string" minOccurs="0" maxOccurs="1">
  <xs:annotation>
    <xs:documentation>The Date timestamp recorded in the email.</xs:documentation>
  </xs:annotation>
</xs:element>

[at055612]

Fixed in 4.1.0