unit tests and pkg version commits

src/isnd/Data/Package.cs

@@ -27,7 +27,21 @@ namespace isnd.Data
         [JsonIgnore]
 
         public virtual List<PackageVersion> Versions { get; set; }
-        public string CommitId { get; set; }
+
+        /// <summary>
+        /// Latest package version put, or post, 
+        /// or { delete when no more active version }.
+        /// </summary>
+        /// <value></value>
+        [Required][JsonIgnore]
+        public long CommitNId { get; set ; }
+
+        [NotMapped]
+        public string CommitId { get => CommitNId.ToString(); }
+
+        [ForeignKey("CommitNId")]
+
+        public virtual Commit LatestVersion{ get; set; }
         public DateTime CommitTimeStamp { get; set; }
     }
 }