add version to the updatechecker file

src/updatechecker.js

@@ -22,15 +22,17 @@ var apps = require('./apps.js'),
     users = require('./users.js');
 
 function setUpdateInfo(state) {
-    console.dir(state);
     // appid -> update info { creationDate, manifest }
     // box -> { version, changelog, upgrade, sourceTarballUrl }
+    state.version = 2;
     safe.fs.writeFileSync(paths.UPDATE_CHECKER_FILE, JSON.stringify(state, null, 4), 'utf8');
 }
 
 function getUpdateInfo() {
     const state = safe.JSON.parse(safe.fs.readFileSync(paths.UPDATE_CHECKER_FILE, 'utf8'));
-    return state || {};
+    if (!state || state.version !== 2) return {};
+    delete state.version;
+    return state;
 }
 
 function checkAppUpdates(options, callback) {