0.01: New App!
0.02: Make overriding the HRM event optional
      Emit BTHRM event for external sensor
      Add recorder app plugin
0.03: Prevent readings from internal sensor mixing into BT values
      Mark events with src property
      Show actual source of event in app
0.04: Automatically reconnect BT sensor
      App buzzes if no BTHRM events for more than 3 seconds