Fixing the bug with connections on database make restore fail (#473)

* closing the connections that don't need to be open and keeping track of the connections that should stay open

src/Microsoft.SqlTools.ServiceLayer/Connection/DatabaseFullAccessException.cs

@@ -0,0 +1,28 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+
+namespace Microsoft.SqlTools.ServiceLayer.Connection
+{
+    public class DatabaseFullAccessException: Exception
+    {
+        public DatabaseFullAccessException()
+            : base()
+        {
+        }
+
+        public DatabaseFullAccessException(string message, Exception exception)
+            : base(message, exception)
+        {
+        }
+
+
+        public DatabaseFullAccessException(string message)
+            : base(message)
+        {
+        }
+    }
+}