Further work on CSHARP-257. Added Capacity property to BsonArray.

Bson/ObjectModel/BsonArray.cs

@@ -152,6 +152,14 @@ namespace MongoDB.Bson {
         #endregion
 
         #region public properties
+        /// <summary>
+        /// Gets or sets the total number of elements the internal data structure can hold without resizing.
+        /// </summary>
+        public int Capacity {
+            get { return values.Capacity; }
+            set { values.Capacity = value; }
+        }
+
         /// <summary>
         /// Gets the count of array elements.
         /// </summary>

BsonUnitTests/ObjectModel/BsonArrayTests.cs

@@ -26,6 +26,14 @@ using MongoDB.Bson.IO;
 namespace MongoDB.BsonUnitTests {
     [TestFixture]
     public class BsonArrayTests {
+        [Test]
+        public void TestCapacity() {
+            var array = new BsonArray(4);
+            Assert.AreEqual(4, array.Capacity);
+            array.Capacity = 8;
+            Assert.AreEqual(8, array.Capacity);
+        }
+
         [Test]
         public void TestCreateBooleanArray() {
             var values = new Boolean[] { true, false };