Add mastering texts.

Marechai.Database/Models/MasteringText.cs

@@ -0,0 +1,15 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Marechai.Database.Models
+{
+    public class MasteringText : BaseModel<ulong>
+    {
+        public MasteringTextType Type { get; set; }
+        [Required]
+        public string Text { get;  set; }
+        public short? Side  { get; set; }
+        public short? Layer { get; set; }
+        [Required]
+        public virtual Media Media { get; set; }
+    }
+}