Do not start receive pipe unless we have handle to camera. Closes #79.

Additionally, upon exiting clear all outstanding UI handler requests
so that the toast notification does not appear upon exiting
application.
Merge branch 'ticket-79' into ticket-68
Stop logging message data since it might not be text based
Added the following performance metrics for QR code transmission
  * Rx: Time to complete message after 1st valid QR code read.
  * Rx: Number of frames recieved from camera
  * Rx: Number of frames with QR coded detected in it
  * Rx: Number of frames with detected QR codes
  * Rx: Number of duplicate QR codes decoded
  * Tx: Whether QR code labels are displayed.