Use i18n for tab switch message.

_locales/en/messages.json

@@ -821,12 +821,18 @@
     "firmwareFlasherReleaseDate": {
         "message": "Date:"
     },
+    "firmwareFlasherReleaseStatus": {
+        "message": "State:"
+    },
     "firmwareFlasherReleaseTarget": {
         "message": "Target:"
     },
     "firmwareFlasherReleaseFile": {
         "message": "Binary:"
     },
+    "firmwareFlasherReleaseStatusReleaseCandidate": {
+        "message": "<span style=\"color: red\">IMPORTANT: This firmware release is currently marked as a release candidate.  Please report any issues immediately.</span>"
+    },
     "firmwareFlasherReleaseFileUrl": {
         "message": "Download manually."
     },

main.js

@@ -63,7 +63,7 @@ $(document).ready(function () {
                 tab = $(self).parent().prop('class');
 
             if (!CONFIGURATOR.connectionValid) {
-                GUI.log('tabSwitchConnectionRequired');
+                GUI.log(chrome.i18n.getMessage('tabSwitchConnectionRequired'));
                 return;
             }