Moved and renamed the scripts to fit with git.

These changes require documentation updates, updates of
the release spreadsheet and the buildbot side.

BUG=chromium:451975
TBR=tandrii@chromium.org
NOTRY=true
LOG=n

Review URL: https://codereview.chromium.org/868473004

Cr-Commit-Position: refs/heads/master@{#26271}