Clean up old releases

src/Artemis.Storage/Entities/General/ReleaseEntity.cs

@@ -7,6 +7,7 @@ public class ReleaseEntity
     public Guid Id { get; set; }
     
     public string Version { get; set; }
+    public string ReleaseId { get; set; }
     public ReleaseEntityStatus Status { get; set; }
     public DateTimeOffset? InstalledAt { get; set; }
 }
@@ -15,5 +16,6 @@ public enum ReleaseEntityStatus
 {
     Queued,
     Installed,
-    Historical
+    Historical,
+    Unknown
 }