Add step printer to annotator.py.
Add step printer to annotator.py.

This will print the step command and other relevant information for every step.

R=iannucci@chromium.org, xusydoc@chromium.org

Review URL: https://chromiumcodereview.appspot.com/16013004

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@202200 0039d316-1c4b-4281-b951-d872f2087c98

luci/recipes-py,shishkander/recipes-py,shishkander/recipes-py,luci/recipes-py