BenchmarkReader is capable of reading standard benchmark files into
Result objects and writing those Result objects back out to a Writer.

Change-Id: I022221f53b5d3ce1de7e8e7b74d265a50ac4a0eb
Reviewed-on: https://go-review.googlesource.com/34627Reviewed-by: Russ Cox <rsc@golang.org>

This creates the skeleton of an AppEngine app for perfdata.golang.org
and adds an initial implementation of /upload that saves the provided
file into Cloud Storage.

Change-Id: I1fe19b27841ab62aad146d1d1019996634012d35
Reviewed-on: https://go-review.googlesource.com/34620Reviewed-by: Russ Cox <rsc@golang.org>