Added device identifier, APIs for updating token by identifier, Device creation/update upon signin.

src/Sql/dbo/Stored Procedures/Device_ReadByIdentifierUserId.sql

@@ -0,0 +1,15 @@
+CREATE PROCEDURE [dbo].[Device_ReadByIdentifierUserId]
+    @UserId UNIQUEIDENTIFIER,
+    @Identifier NVARCHAR(50)
+AS
+BEGIN
+    SET NOCOUNT ON
+
+    SELECT
+        *
+    FROM
+        [dbo].[DeviceView]
+    WHERE
+        [UserId] = @UserId
+        AND [Identifier] = @Identifier
+END