rebaseline_server: add tabs, and ability to submit new baselines to the server

Tabs allow the user to divide the tests into groups:
hide these for now, approve these, etc.

(SkipBuildbotRuns)

R=borenet@google.com

Review URL: https://codereview.chromium.org/28903008

git-svn-id: http://skia.googlecode.com/svn/trunk@11915 2bbb7eff-a529-9590-31e7-b0007b416f81
5 files changed