Update package name

Author: JunTaoLuo

src/Microsoft.AspNetCore.Server.Testing/project.json

@@ -17,7 +17,7 @@
     "Microsoft.AspNetCore.Testing": "1.0.0-*",
     "Microsoft.Extensions.Logging.Abstractions": "1.0.0-*",
     "Microsoft.Extensions.PlatformAbstractions": "1.0.0-*",
-    "Microsoft.Extensions.ProcessHelper.Sources": {
+    "Microsoft.Extensions.Process.Sources": {
       "type": "build",
       "version": "1.0.0-*"
     },