Add managed connection pooling and execution locking

DynamORM.Tests/Helpers/PoolingTests.cs

@@ -92,9 +92,10 @@ namespace DynamORM.Tests.Helpers
             finally
             {
                 // Remove for next tests
-                Database.Dispose();
+                if (Database != null)
+                    Database.Dispose();
                 Database = null;
             }
         }
     }
-}
+}