Fix: Add Givenname and Surname to Users Table (coscine/issues#280)

coscine/issues#280

src/Migrator/Migrations/Migration201909160919UserEnhancement.cs

+using FluentMigrator;
+namespace Coscine.Database.Migration.Migrations
+{
+    //yyyymmddhhmm
+    [Migration(201909160919)]
+    public class Migration201909160919UserEnhancement : FluentMigrator.Migration
+    {
+        public override void Down()
+        {
+            Delete.Column("Givenname").FromTable("Users");
+            Delete.Column("Surname").FromTable("Users");
+        }
+
+        public override void Up()
+        {
+            Alter.Table("Users").AddColumn("Givenname").AsString(200).Nullable();
+            Alter.Table("Users").AddColumn("Surname").AsString(200).Nullable();
+        }
+    }
+}