Improve manage.py to automate CL creation further.

It's tedious to write CL description manually. Make manage.py make the CL
description for me.

R=dpranke@chromium.org
BUG=98637

Review URL: https://codereview.chromium.org/1203753002

Cr-Commit-Position: refs/heads/master@{#335765}
1 file changed