Update push payload definitions to adhere to Apple specifications
Update push payload definitions to adhere to Apple specifications

- The .NET push client expects the push message payload to be exactly
as per Apple definitions which means it expects the aps payload to be
in an “aps” property of the dictionary.
- The Node implementation modifies the payload dictionary by adding a
new dictionary keyed by the string “aps” and adds all original
dictionary contents to it.
- To have the same set of tests to work with both the backends, this
commit updates the payload definitions to adhere to the Apple
specifications.

Azure/azure-mobile-apps-ios-client,Azure/azure-mobile-apps-ios-client,Azure/azure-mobile-apps-ios-client,Azure/azure-mobile-apps-ios-client