start most cron jobs only after activation

Importing the db might take some time. If a cron runs in the middle,
it crashes.

TypeError: Cannot read property 'domain' of undefined
    at Object.fqdn (/home/yellowtent/box/src/domains.js:126:111)
    at /home/yellowtent/box/src/apps.js:460:36
    at /home/yellowtent/box/node_modules/async/dist/async.js:3110:16
    at replenish (/home/yellowtent/box/node_modules/async/dist/async.js:1011:17)
    at /home/yellowtent/box/node_modules/async/dist/async.js:1016:9
    at eachLimit$1 (/home/yellowtent/box/node_modules/async/dist/async.js:3196:24)
    at Object.<anonymous> (/home/yellowtent/box/node_modules/async/dist/async.js:1046:16)
    at /home/yellowtent/box/src/apps.js:458:19
    at /home/yellowtent/box/src/appdb.js:232:13
    at Query.args.(anonymous function) [as _callback] (/home/yellowtent/box/src/database.js

src/cloudron.js

@@ -74,7 +74,7 @@ function initialize(callback) {
     async.series([
         settings.initialize,
         reverseProxy.configureDefaultServer,
-        cron.initialize, // required for caas heartbeat before activation
+        cron.startPreActivationJobs,
         onActivated
     ], callback);
 }
@@ -83,7 +83,7 @@ function uninitialize(callback) {
     assert.strictEqual(typeof callback, 'function');
 
     async.series([
-        cron.uninitialize,
+        cron.stopJobs,
         platform.stop,
         settings.uninitialize
     ], callback);
@@ -99,7 +99,10 @@ function onActivated(callback) {
         if (error) return callback(new CloudronError(CloudronError.INTERNAL_ERROR, error));
         if (!count) return callback(); // not activated
 
-        platform.start(callback);
+        async.series([
+            platform.start,
+            cron.startPostActivationJobs
+        ], callback);
     });
 }