Remove direct Microsoft.NETCore.Platforms dependency.

- Microsoft.NETCore.App now pulls this package in.

aspnet/Coherence-Signed#344

Author: N. Taylor Mullen

samples/StaticFileSample/project.json

@@ -3,7 +3,6 @@
     "emitEntryPoint": true
   },
   "dependencies": {
-    "Microsoft.NETCore.Platforms": "1.0.1-*",
     "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0-*",
     "Microsoft.AspNetCore.Server.Kestrel": "1.0.0-*",
     "Microsoft.AspNetCore.StaticFiles": "1.0.0-*",

test/Microsoft.AspNetCore.StaticFiles.Tests/project.json

@@ -18,7 +18,6 @@
   "dependencies": {
     "System.Runtime.InteropServices.RuntimeInformation": "4.0.0-*",
     "dotnet-test-xunit": "1.0.0-*",
-    "Microsoft.NETCore.Platforms": "1.0.1-*",
     "Microsoft.AspNetCore.StaticFiles": "1.0.0-*",
     "Microsoft.AspNetCore.TestHost": "1.0.0-*",
     "Microsoft.AspNetCore.Testing": "1.0.0-*",