rework scheduled tasks in preparation of common project going portable

MediaBrowser.Common.Implementations/Cryptography/CryptographyProvider.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Security.Cryptography;
+using System.Text;
+using MediaBrowser.Model.Cryptography;
+
+namespace MediaBrowser.Common.Implementations.Cryptography
+{
+    public class CryptographyProvider : ICryptographyProvider
+    {
+        public Guid GetMD5(string str)
+        {
+            using (var provider = MD5.Create())
+            {
+                return new Guid(provider.ComputeHash(Encoding.Unicode.GetBytes(str)));
+            }
+        }
+    }
+}