ENH: QR reader app support for return text from OVLcheckincheckout.php

[BobGlicksman]

The current QR reader app does an https GET on the url that is encoded on a badge QR code. The url endpoint runs the script OVLcheckincheckout.php on the web hosting service. The app currently processes only the web response code, indicting a "web error" if the response code is other than 200 (if the response code is 200, then it is assumed that the checkin or checkout succeeded).

The aforementioned PHP script checks for conditions like "previous visit record not found" and returns a text string to this effect, on a 200 response code. The PHP script does not return text to say "OK". An enhancement would be to have the script return "OK" if the checkin or checkout was processed correctly, or else a message that the user of the app should see. The app should then be enhanced to process the response text accordingly if the response code is 200. That is, any text that was other than "OK" would be displayed by the app, as opposed to "web error" that is today's (not very informative) default.