Convert project to not portable, just a standard .NET 4.5 library, so that
.NET APIs necessary for debugging requests via Fiddler are enabled (This
enabled "Proxy" property on HttpWebRequest - this code is currently
disabled).  Added method on WebApi2 ActionTrackingAttribute to read
customvariables set on the HttpRequestMessage and add them as Google
Analytics Custom Variables.  Allows setting custom variables with values
computed within controller actions. Send data to Google Analytics via
ActionFilter's "after event" OnActionExecutedAsync rather than its "before
event" OnActionExecutingAsync allowing this filter to read values that
were computed during the execution of its associated controller action.