Adding registerPushNotificationHandler method
fixed registerPushNotificationHandler
Moving push registraton helper function out of com.salesforce.plugin.oauth
boot config is under key bootConfig
Merge from upstream
Merge branch 'unstable' of github.com:forcedotcom/SalesforceMobileSDK-Shared into unstable
If they use the PushPlugin from phonegap, iOS message won't have a event field
Merge pull request #185 from wmathurin/unstable

Helper function for push registration