Change version to .NET Core 2.0

Author: shawnwildermuth

readme.md

@@ -8,7 +8,7 @@ To install, use the Nuget "WilderMinds.MetaWeblog":
   PM> Install-Package WilderMinds.MetaWeblog
 ```
 
-This project is an ASP.NET Core 1.0 Middleware component to support the MetaWeblog API 
+This project is an ASP.NET Core 2.0 Middleware component to support the MetaWeblog API 
 that WordPress and Windows LiveWriter uses to support adding and editing of content
 in blogs.