Created the Contracts and Client PCL projects

Initially it is a copy paste from the original projects, and altering
the namespaces.
Removed Nuget and IPackage dependency

No Nuget PCL alternative was found. And since this PCL's original
purpose is to enable Kudu clients for devices, the use case of depending
on IPackage and Nuget is minimal in this case.
Created local TraceEventType enum

No PCL alternative for System.Diagnostics. And we don't really need
System.Diagnostics for the Enum only