jebeck/new join wizards and boluses

Pretty much ready to merge this into master @kentquirk, although I'd like a chance to confirm it's operational myself when you've got good data again that I can test it on.
Why not ditch "bolusesToJoin" and change this code to

```
var bolusId = wizard.bolus;
if (bolusId == null) {
  bolusId = wizard.joinKey;
}

if (bolusId != null) {
  wizard.bolus = allBoluses[joinKey]
}
```