Fix bugs introduced by Wear support

Two bugs, one commit. First, don't do the group/groupSummary stuff if
there's only one notification. Wear seems to want to put both of them
into the stream.

Second, use unique PendingIntent requestCodes, so that the
notifications and the widget don't conflict. I may need to add action
codes if I have more things, but right now I'm using the id (cast to
int) for the requestCode for intents that have an id extra hardcoded,
and -1 for the widget, where it will update automatically.