Add Icons application for serving website icons.

src/Icons/Models/Icon.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.Serialization;
+using System.Threading.Tasks;
+
+namespace Icons.Models
+{
+    [Serializable]
+    public class Icon
+    {
+
+        public byte[] Image { get; }
+
+        public string Format { get; }
+        
+        public DateTime CreatedAt { get; }
+
+        public Icon(byte[] image, string format)
+        {
+            this.Image = image;
+            this.Format = format;
+            this.CreatedAt = DateTime.Now;
+        }
+
+        public bool HasNotExpired()
+        {
+            return CreatedAt > DateTime.Now.AddDays(-1);
+        }
+    }
+}