de facto standard LOW and HIGH values

Disregard brand of device when considering glucose values.  By de facto usage,
the meaning of LOW and HIGH within Nightscout means that glucose is beyond limits.
LOW means 40 or lower.  HIGH means 400 or higher.  Both tend to invite
questioning therapy options, including inspecting if the device is working
correctly, as well as potential treatment options.

lib/sandbox.js

@@ -235,10 +235,9 @@ function init () {
   };
 
   sbx.displayBg = function displayBg (entry) {
-    var isDex = entry && (!entry.device || entry.device === 'dexcom' || entry.device === 'share2');
-    if (isDex && Number(entry.mgdl) === 39) {
+    if (Number(entry.mgdl) === 39) {
       return 'LOW';
-    } else if (isDex && Number(entry.mgdl) === 401) {
+    } else if (Number(entry.mgdl) === 401) {
       return 'HIGH';
     } else {
       return sbx.scaleEntry(entry);