Merge pull request #635 from andrerod/dev

Merge reviewed PRs
Move APNS expiry to payload only, Adding SAS support, moving hub CRUD to
service bus
Create wnsHeader sub element
Improve error object usage
Merge pull request #52 from andrerod/notificationadjusts

#636 & #634: Implementing SAS for notification hubs and API adjustments
Merge pull request #641 from andrerod/dev

Merge reviewed changes