Supporting SQL DW in Object explorer (#380)

* supporting sql dw in oe

src/Microsoft.SqlTools.ServiceLayer/ObjectExplorer/SmoModel/SmoQuerier.cs

@@ -72,9 +72,26 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer.SmoModel
         {
             return true;
         }
-        
 
-       
+        /// <summary>
+        /// Returns true if the querier is valid for the given server version
+        /// </summary>
+        /// <param name="serverValidFor"></param>
+        /// <returns></returns>
+        public bool IsValidFor(ValidForFlag serverValidFor)
+        {
+            return ServerVersionHelper.IsValidFor(serverValidFor,  ValidFor);
+        }
+
+        /// <summary>
+        /// Indicates which platforms the querier is valid for
+        /// </summary>
+        public virtual ValidForFlag ValidFor
+        {
+            get
+            {
+                return ValidForFlag.All;
+            }
+        }
     }
-    
 }