lts-triage-v2.py: sort commits by committer date

1. Add a "committer date" column and sort commits by this field.
2. Add a "To be cherry-picked" column for future automation [1].
   - Value will be "N" if the commit has already been cherry-picked
     to the LTS branch, otherwise "Y".

[1]: https://linaro.atlassian.net/browse/TFC-750

Change-Id: I6a4ecbf9f051a0d428e251915c3867261ef458f5
Signed-off-by: Arthur She <arthur.she@linaro.org>
1 file changed