[webapi][XWALK-2450] Fix bug for contactsmanager

- Fix case bug for contactsmanager
- Failure analysis: The Contact.id attribute of type should be string by spec, but get number on crosswalk-9.37.194.0

Impacted tests(approved): new 0, update 4, delete 0
Unit test platform: [Android]
Unit test result summary: pass 3, fail 1, block 0
Contactschange event will be fired by clear method and save method. In this case run method will be ran first, the value of e.added[0] is undefined, but we need wait the event be fired by save method again.