add extension_list example (#281)

- Created an example of extension policy
- Added C# binding support of .NET framework 4.0 and created a Nuget
  spec for it.
- Added a pytest in python bindings to test the extension policy and the
  python binding
- Restructured the example and Csharp binding directories due to above
  changes.
- Added copyrights.
- Added a Windows workflow for .NET 4.0 build and test.

bindings/csharp/net40/Program.cs

@@ -0,0 +1,65 @@
+//-----------------------------------------------------------------------
+// <copyright file="Program.cs" company="Microsoft">
+//    Copyright (c)2012 Microsoft. All rights reserved.
+// </copyright>
+// <summary>
+//    Contains code to test the Regorus Policy Engine base class for C#
+// and .NET4.0 bindings. It can be built and tested in Windows only. 
+// </summary>
+//-----------------------------------------------------------------------
+using System;
+using System.Text;
+
+using System.Diagnostics;
+using Microsoft.WindowsAzure.Regorus.IaaS;
+
+namespace regoregorus_test
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            long nanosecPerTick = (1000L * 1000L * 1000L) / Stopwatch.Frequency;
+            var w = new Stopwatch();
+            w.Restart();
+
+            var engine = new RegorusPolicyEngine();
+
+            w.Stop();
+            var newEngineTicks = w.ElapsedTicks;
+
+
+            w.Restart();
+
+            // Load policies and data.
+            engine.AddPolicyFromFile("../../../examples/extension_list/agent_extension_policy.rego");
+            engine.AddDataFromJsonFile("../../../examples/extension_list/agent-extension-data-allow-only.json");
+
+
+            w.Stop();
+            var loadPoliciesTicks = w.ElapsedTicks;
+
+
+            w.Restart();
+
+            // Set input and eval query.
+            engine.SetInputFromJsonFile("../../../examples/extension_list/agent-extension-input.json");
+            var results = engine.EvalQuery("data.agent_extension_policy.extensions_to_download=x");
+            Console.WriteLine("Download query test: \n {0}", results);
+
+            results = engine.EvalQuery("data.agent_extension_policy.extensions_validated");
+        
+            Console.WriteLine("Signing validation test: \n {0}", results);
+
+            engine.Dispose();
+
+            w.Stop();
+            var evalTicks = w.ElapsedTicks;
+
+            Console.WriteLine("Engine creation took {0} msecs", (newEngineTicks * nanosecPerTick) / (1000.0 * 1000.0));
+            Console.WriteLine("Load policies and data took {0} msecs", (loadPoliciesTicks * nanosecPerTick) / (1000.0 * 1000.0));
+            Console.WriteLine("EvalQuery and print results took {0} msecs", (evalTicks * nanosecPerTick) / (1000.0 * 1000.0));
+        }
+    }
+}
+