Add GlobalSuppressions for unit tests

Author: jcansdale

test/GitHub.VisualStudio.UnitTests/GlobalSuppressions.cs

@@ -0,0 +1,10 @@
+
+// This file is used by Code Analysis to maintain SuppressMessage 
+// attributes that are applied to this project.
+// Project-level suppressions either have no target or are given 
+// a specific target and scoped to a namespace, type, member, etc.
+
+[assembly: System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1034:Nested types should not be visible",
+    Justification = "It's okay for nested unit test types to be visible")]
+[assembly: System.Diagnostics.CodeAnalysis.SuppressMessage("Naming", "CA1707:Identifiers should not contain underscores",
+    Justification = "It's okay for unit test names to contain underscores")]