Add v2 of the Hosting Service and build nuget packages for it (#675)

* Port v2 of Hosting service to SqlToolsService
- Renamed project to .v2 so that existing hosted service isn't impacted
- Copied over the CoreServices project which contains ConnectionServiceCore and other reusable services for anything interacting with MSSQL
- Ported unit test project across and verified tests run.

* Nuget package support for reusable DLLs

* Use 1.1 version per Karl's suggestion

* Use correct license URL and project URL

* Use new SMO packages

test/Microsoft.SqlTools.Hosting.UnitTests/CommonObjects.cs

@@ -0,0 +1,67 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using Microsoft.SqlTools.Hosting.Contracts;
+using Microsoft.SqlTools.Hosting.Contracts.Internal;
+using Microsoft.SqlTools.Hosting.Protocol;
+using Newtonsoft.Json.Linq;
+
+namespace Microsoft.SqlTools.Hosting.UnitTests
+{
+    public static class CommonObjects
+    {
+        public const string MessageId = "123";
+        
+        public static readonly RequestType<TestMessageContents, TestMessageContents> RequestType = 
+            RequestType<TestMessageContents, TestMessageContents>.Create("test/request");
+
+        public static readonly EventType<TestMessageContents> EventType = 
+            EventType<TestMessageContents>.Create("test/event");
+        
+        public static readonly Message RequestMessage =
+            Message.CreateRequest(RequestType, MessageId, TestMessageContents.DefaultInstance);
+
+        public static readonly Message ResponseMessage =
+            Message.CreateResponse(MessageId, TestMessageContents.DefaultInstance);
+        
+        public static readonly Message EventMessage =
+            Message.CreateEvent(EventType, TestMessageContents.DefaultInstance);
+
+        public static class TestErrorContents
+        {
+            public static readonly JToken SerializedContents = JToken.Parse("{\"code\": 123, \"message\": \"error\"}");
+            public static readonly Error DefaultInstance = new Error {Code = 123, Message = "error"};
+        }
+        
+        public class TestMessageContents : IEquatable<TestMessageContents>
+        {
+            public const string JsonContents = "{\"someField\": \"Some value\", \"number\": 42}";
+            public static readonly JToken SerializedContents = JToken.Parse(JsonContents);
+            public static readonly TestMessageContents DefaultInstance = new TestMessageContents {Number = 42, SomeField = "Some value"};
+
+            public string SomeField { get; set; }
+            public int Number { get; set; }
+
+            public bool Equals(TestMessageContents other)
+            {
+                return string.Equals(SomeField, other.SomeField) 
+                       && Number == other.Number;
+            }
+
+            public static bool operator ==(TestMessageContents obj1, TestMessageContents obj2)
+            {
+                bool bothNull = ReferenceEquals(obj1, null) && ReferenceEquals(obj2, null);
+                bool someNull = ReferenceEquals(obj1, null) || ReferenceEquals(obj2, null);
+                return bothNull || !someNull && obj1.Equals(obj2);
+            }
+
+            public static bool operator !=(TestMessageContents obj1, TestMessageContents obj2)
+            {
+                return !(obj1 == obj2);
+            }
+        }
+    }
+}