Modified how attachments are pushed to the API.

Added support for BMP and GIF image types.

PWAPPv2/Source/Attachments/AttachmentResponse.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace PWAPPv2.Source.Attachments
+{
+    public class AttachmentResponse
+    {
+    }
+}