Support for OneSignal push notification

Added support for OneSignal push notification.

Update backend version

update backed version to support limiting the nested collection items of depth 3

Fix: Browser back and forward button does not change the content

I have added a defensive check, whether the current path is undefined or null in the navigateToPage () function and taking window.location.pathname as default if it's undefined.

Fix SEO issue

Pass missing SEO callback to Isomorphic handler

Integrate SEO

1. Integrate SEO package
2. Add missing error handler parameters

Added error handling

Define custom application exceptions and handle those exceptions in isomorphic handler.

Add basic error handling

v0.2.11

Bump the version