Add ability to rebaseline skimage to rebaseline.py

Add ability to rebaseline skimage to rebaseline.py

Skip pattern matching for skimage, since the skimage results do not
match the pattern.

Automatically fill in expectations_root and actuals_base_url when
--skimage is specified.

Requires a change to move the expectations files to the right place.
Depends on https://codereview.chromium.org/26734006

(SkipBuildBotRuns)

BUG=skia:1466
R=epoger@google.com

Review URL: https://codereview.chromium.org/26666004

git-svn-id: http://skia.googlecode.com/svn/trunk@11717 2bbb7eff-a529-9590-31e7-b0007b416f81