rebaseline_server: serve JSON from static file, rather than generating it live

BUG=skia:1455, skia:2230
NOTREECHECKS=True
NOTRY=True
R=borenet@google.com

Author: epoger@google.com

Review URL: https://codereview.chromium.org/197213033

git-svn-id: http://skia.googlecode.com/svn/trunk@13876 2bbb7eff-a529-9590-31e7-b0007b416f81
6 files changed