Check wifi connectivity only

[LukasKorba]

The background processing request hold a flag

 request.requiresNetworkConnectivity = true

The BGTask is triggered by the system only when the iPhone is currently connected to the internet. The issue with this flag is that any connectivity will trigger the task. There is no API that can specify the type of the connectivity.

We want to trigger syncing for wifi only connectivity so the solution is to let the system to trigger the BGTask but check the connectivity in a custom solution way. Only when we confirm the wifi is present, we start the synchronizer.