2019 Janurary update

• Application Insights exporter improvements - now understands http attributes
  and process links, annotations and messages.
• ASP.NET Core collector now uses http.route for the span name.
• Initial implementation of Resource Specification.
• Plug in to collect Redis calls made using StackExchange.Redis package.
• Object of type ISpanData can be created using only Abstractions package.
• Number of minor APIs adjustments.