Remove unused FileSystem dependencies.

Author: Tratcher

src/Microsoft.AspNet.Diagnostics/project.json

@@ -17,8 +17,6 @@
         "System.Diagnostics.Tools": "4.0.0.0",
         "System.Globalization": "4.0.10.0",
         "System.IO": "4.0.0.0",
-        "System.IO.FileSystem": "4.0.0.0",
-        "System.IO.FileSystem.Primitives": "4.0.0.0",
         "System.Linq": "4.0.0.0",
         "System.Reflection": "4.0.10.0",
         "System.Resources.ResourceManager": "4.0.0.0",