Implement `SqlOrd` for date and time types
Implement `SqlOrd` for date and time types

I missed this when I added them, but they can definitely be ordered.

diesel-rs/diesel,SoftwareWarlock/diesel,mcasper/diesel,mcasper/diesel,sgrif/diesel,cascalheira/diesel,tohou/diesel,sgrif/diesel,SoftwareWarlock/diesel,tohou/diesel,cascalheira/diesel,diesel-rs/diesel