Move some classes and restructure.

src/WireMock/Server/IRespondWithAProvider.cs

@@ -0,0 +1,16 @@
+namespace WireMock.Server
+{
+    /// <summary>
+    /// IRespondWithAProvider
+    /// </summary>
+    public interface IRespondWithAProvider
+    {
+        /// <summary>
+        /// The respond with.
+        /// </summary>
+        /// <param name="provider">
+        /// The provider.
+        /// </param>
+        void RespondWith(IProvideResponses provider);
+    }
+}