Switch to using DI to acquire Node instances. Bump versions to alpha2.

Microsoft.AspNet.NodeServices/INodeInstance.cs

@@ -0,0 +1,10 @@
+using System;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNet.NodeServices {
+    public interface INodeServices : IDisposable {    
+        Task<string> Invoke(string moduleName, params object[] args);
+    
+        Task<string> InvokeExport(string moduleName, string exportedFunctionName, params object[] args);
+    }
+}