Adjustments to the semantics of status events

@kentquirk @jebeck 

These are some changes to the data model to (hopefully) make it a bit easier to work with the suspensions.  Please read it over and let me know if things need more clarification.
You're saying with this that you want to keep a record of pump suspensions and that there are very specific semantics to those suspensions. In that case, I think we should call it that and create a specific pump-suspend (or something) record type. 

If your intention is that device-meta is a generalized bucket of device information, I think you're putting too much into it by defining that they come in pairs and that suspend always has to happen first.

Also, what happens when a pump has a resume record but no previous suspend record? (Perhaps the first time it's turned on?)