Add missing MemoryString(capacity) API

Author: mythz

src/ServiceStack.Text/RecyclableMemoryStream.cs

@@ -48,6 +48,13 @@ public static MemoryStream GetStream()
                 : new MemoryStream();
         }
 
+        public static MemoryStream GetStream(int capacity)
+        {
+            return UseRecyclableMemoryStream
+                ? RecyclableInstance.GetStream(typeof(MemoryStreamFactory).Name, capacity)
+                : new MemoryStream(capacity);
+        }
+
         public static MemoryStream GetStream(byte[] bytes)
         {
             return UseRecyclableMemoryStream
@@ -67,6 +74,11 @@ public static MemoryStream CreateMemoryStream()
             return new MemoryStream();
         }
 
+        public static MemoryStream GetStream(int capacity)
+        {
+            return new MemoryStream(capacity);
+        }
+
         public static MemoryStream CreateMemoryStream(byte[] bytes)
         {
             return new MemoryStream(bytes);