Avoid spurious request for /qr?text={{myID}} (fixes #1679)

gui/index.html

@@ -463,7 +463,7 @@
 
   <modal id="idqr" large="yes" status="info" close="yes" icon="qrcode" title="{{'Device Identification' | translate}} &mdash; {{deviceName(thisDevice())}}">
     <div class="well well-sm text-monospace text-center">{{myID}}</div>
-    <img ng-if="myID" class="center-block img-thumbnail" src="qr/?text={{myID}}"/>
+    <img ng-if="myID" class="center-block img-thumbnail" ng-src="qr/?text={{myID}}"/>
   </modal>
 
   <!-- Device editor modal -->