RFR: 193: git-pr: add flag --publish

[Erik Helin]

Hi all,

please review this patch that adds the flag `--publish` to `git-pr create`
(also configurable). When `--publish` is set then `git-pr` will call
`git-publish --quiet` if the branch is not yet pushed to the remote. This
avoids having to type `git publish && git pr create` when creating pull
requests from the command-line.

Note that I had to update `git-publish` a bit to fully support the `--quiet`
flag.

Thanks,
Erik

- [x] Manual testing of `git-pr create --publish`

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Commits:
 - c5649967: skara-193

Changes: https://git.openjdk.java.net/skara/pull/317/files
 Webrev: https://webrevs.openjdk.java.net/skara/317/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-193
  Stats: 31 lines in 2 files changed: 16 ins; 0 del; 15 mod
  Patch: https://git.openjdk.java.net/skara/pull/317.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/317/head:pull/317

PR: https://git.openjdk.java.net/skara/pull/317