Added migrations

EventArguments/MigrationStartedEventArgs.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace DbTools.EventArguments {
+    public delegate void MigrationStartedEventHandler(object sender, MigrationStartedEventArgs e);
+
+    public class MigrationStartedEventArgs : EventArgs {
+        public string MigrationName { get; set; }
+        public int Remaining { get; set; }
+
+        public MigrationStartedEventArgs() { }
+        public MigrationStartedEventArgs(string migrationName, int remaining) {
+            MigrationName = migrationName;
+            Remaining = remaining;
+        }
+    }
+}