Organize classes better

Closes #94

Octokit/Models/Request/MilestoneRequest.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+namespace Octokit
+{
+    public class MilestoneRequest
+    {
+        static readonly MilestoneRequest _defaultParameterValues = new MilestoneRequest();
+
+        public MilestoneRequest()
+        {
+            State = ItemState.Open;
+            SortProperty = MilestoneSort.DueDate;
+            SortDirection = SortDirection.Ascending;
+        }
+
+        public ItemState State { get; set; }
+        public MilestoneSort SortProperty { get; set; }
+        public SortDirection SortDirection { get; set; }
+
+        /// <summary>
+        /// Returns a dictionary of query string parameters that represent this request. Only values that
+        /// do not have default values are in the dictionary. If everything is default, this returns an
+        /// empty dictionary.
+        /// </summary>
+        [SuppressMessage("Microsoft.Globalization", "CA1308:NormalizeStringsToUppercase",
+            Justification = "The API expects lowercase")]
+        public virtual IDictionary<string, string> ToParametersDictionary()
+        {
+            var parameters = new Dictionary<string, string>();
+
+            if (State != _defaultParameterValues.State)
+            {
+                parameters.Add("state", "closed");
+            }
+
+            if (SortProperty != _defaultParameterValues.SortProperty)
+            {
+                parameters.Add("sort", "completeness");
+            }
+
+            if (SortDirection != _defaultParameterValues.SortDirection)
+            {
+                parameters.Add("direction", "desc");
+            }
+
+            return parameters;
+        }
+    }
+
+    public enum MilestoneSort
+    {
+        DueDate,
+        Completeness
+    }
+}