support custom pipeline message

[zc2638]

Support cutom pipeline customization to commit message information,
which will help to view associated triggers and debug troubleshooting.

Actual

I create custom build in another pipeline, but I can't see some useful information of these builds on the list.

Expect

I can customize the commit message information when creating custom build, so that it can write the build number triggered by the associated pipeline.

e.g.

# 19  Triggered by build number 15 of root/test
# 18  Triggered by build number 14 of root/test
# 17  Triggered by build number 13 of root/test

[zc2638]

@tphoney I don't know why CI fails, can you give me some pointers?

[tphoney]

I re-kicked the build @zc2638 looks green now. no idea what happened.

[zc2638]

ping @eoinmcafee00