Remove old upgrade notifications

When updating to v0.6 and v0.7, a notification showed up to explain the
changes. These versions are very old and these notifications are not
expected to be shown again, so this change removes those notifications
and the corresponding strings from messages.json.

Change-Id: I83d4ae901044e176495555da03da48e2f7ffcb16
diff --git a/src/background.js b/src/background.js
index 7058875..1770c14 100644
--- a/src/background.js
+++ b/src/background.js
@@ -200,17 +200,7 @@
         if (isoLangs[default_language] != undefined)
           settings.languages[default_language] = default_language;
 
-        chrome.storage.sync.set(settings, function() {
-          chrome.notifications.create('upgradedtostorage', {
-            type: 'basic',
-            iconUrl: 'icons/translate-128.png',
-            title:
-                chrome.i18n.getMessage('notification_upgradedtostorage_title'),
-            message: chrome.i18n.getMessage(
-                'notification_upgradedtostorage_message'),
-            isClickable: true,
-          });
-        });
+        chrome.storage.sync.set(settings);
       }
 
       // Updating from a version previous to v0.7
@@ -222,15 +212,7 @@
           i++;
         }
         delete items.languages;
-        chrome.storage.sync.set(items, _ => {
-          chrome.notifications.create('reorder', {
-            type: 'basic',
-            iconUrl: 'icons/translate-128.png',
-            title: chrome.i18n.getMessage('notification_reorder_title'),
-            message: chrome.i18n.getMessage('notification_reorder_message'),
-            isClickable: true
-          });
-        });
+        chrome.storage.sync.set(items);
       }
 
       // Remove non-existent languages or change with correct language code
@@ -296,8 +278,6 @@
 chrome.notifications.onClicked.addListener(notification_id => {
   switch (notification_id) {
     case 'install':
-    case 'upgradedtostorage':
-    case 'reorder':
       openOptionsPage();
       break;
   }