Notification: I'm going to play! + Location

[CrystalLarsh]

Dependent on implementation of #26 and #10 - per comments.

If we do get notifications up and running and we add this category, that would be a
super valuable notification to hit a button when you say I'm going to play
this game if you select it from the what should we play screen...
Similarly, from the who else is interested, let people know you're going to
play it. Give them the ability to put a location, ie "main hall p4"