Properly access tabris.app in boot.js
Properly access tabris.app in boot.js

With the removal of so-called "service objects" in tabris  2.0,
the cid of tabris.app will differ from its type "tabris.App".

Change-Id: I3cee9703bad109cd97beb4989455958acc29d4c9

eclipsesource/tabris-js,eclipsesource/tabris-js,eclipsesource/tabris-js