Add option for a suspended basal

@jebeck @kentquirk 

This is an extension to the data model to allow a pump to create a meaningful stream of basals in the case of a suspend (i.e. it is possible for an integration to tell us about the actual basals delivered with just basal events).  The idea is that when a suspend actually happens, the pump will now have something that it can use to provide us with meaningful basal information.

Please look this over and comment as soon as you see this, 'cause I am already working on it.
When a suspend occurs to kill the device?  I'm not really sure why it would happen.  My thinking when I included the language was actually more centered around when a suspend goes across scheduled boundaries and like it represents the pump being off or something.

It might be the case that it never happens, but I felt like making suppressed optional and something that should be included was going to be more better.