Update AssemblyNativeVersion to 1.2.0.0 (#79)

Author: josesimoes

source/nanoFramework.CoreLibrary/System/AssemblyInfo2.cs

@@ -1,4 +1,4 @@
-//
+//
 // Copyright (c) 2017 The nanoFramework project contributors
 // Portions Copyright (c) Microsoft Corporation.  All rights reserved.
 // See LICENSE file in the project root for full license information.
@@ -14,4 +14,4 @@
 [assembly: AssemblyProduct("nanoFramework mscorlib")]
 [assembly: AssemblyCopyright("Copyright © nanoFramework Contributors 2017")]
 
-[assembly: AssemblyNativeVersion("1.1.1.7")]
+[assembly: AssemblyNativeVersion("1.2.0.0")]