test-only changes: add more image files to test more skdiff behavior

Tests output order for very vs. slightly different pixels, very vs. slightly different image sizes, etc.

TBR=tomhudson@google.com
Review URL: https://codereview.appspot.com/6213049

git-svn-id: http://skia.googlecode.com/svn/trunk@3977 2bbb7eff-a529-9590-31e7-b0007b416f81
16 files changed