Wrapping up batch separation

Adding unit tests
Fixing things that got brought up from the unit tests

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/Contracts/QueryExecuteCompleteNotification.cs

@@ -17,11 +17,6 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts
         /// </summary>
         public string OwnerUri { get; set; }
 
-        /// <summary>
-        /// Any messages that came back from the server during execution of the query
-        /// </summary>
-        public string[] Messages { get; set; }
-
         /// <summary>
         /// Summaries of the result sets that were returned with the query
         /// </summary>