Feature/autocomp options (#63)

* Enable IntelliSense settings

* Fix up some bugs in the IntelliSense settings.

* Code cleans for PR

* Fix a couple exceptions that are breaks query execute and intellisense.

* Add useLowerCase flag and settings tests

src/Microsoft.SqlTools.ServiceLayer/SqlContext/IntelliSenseSettings.cs

@@ -0,0 +1,53 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.SqlTools.ServiceLayer.SqlContext
+{
+    /// <summary>
+    /// Class for serialization and deserialization of IntelliSense settings
+    /// </summary>
+    public class IntelliSenseSettings
+    {
+        /// <summary>
+        /// Initialize the IntelliSense settings defaults
+        /// </summary>
+        public IntelliSenseSettings()
+        {
+            this.EnableSuggestions = true;
+            this.LowerCaseSuggestions = false;
+            this.EnableDiagnostics = true;
+        }
+
+        /// <summary>
+        /// Gets or sets a flag determining if suggestions are enabled
+        /// </summary>
+        /// <returns></returns>
+        public bool? EnableSuggestions { get; set; }
+
+        /// <summary>
+        /// Gets or sets a flag determining if built-in suggestions should be lowercase
+        /// </summary>
+        public bool? LowerCaseSuggestions { get; set; }
+
+        /// <summary>
+        /// Gets or sets a flag determining if diagnostics are enabled
+        /// </summary>
+        public bool? EnableDiagnostics { get; set; }
+
+        /// <summary>
+        /// Update the Intellisense settings
+        /// </summary>
+        /// <param name="settings"></param>
+        public void Update(IntelliSenseSettings settings)
+        {
+            if (settings != null)
+            {
+                this.EnableSuggestions = settings.EnableSuggestions;
+                this.LowerCaseSuggestions = settings.LowerCaseSuggestions;
+                this.EnableDiagnostics = settings.EnableDiagnostics;
+            }
+        }
+    }
+}