Add the Codeship --skip-ci flag to the staging.tmp commit messages

[bors-ng]

Add the Codeship --skip-ci flag to the staging.tmp commit messages

[timvdalen]

For Codeship, the only way to completely skip CI is by adding a term to the commit message of the tmp commit: https://documentation.codeship.com/basic/getting-started/skipping-builds/

[notriddle]

Okay, then the best way to fix this would be to make the staging.tmp message always contain that magic string.

There are two places it would need to be handled; in the webhook controller, under the status handler (so that the message still matches), and in the batcher (where the message is generated).