RFR: 194: git-pr create --publish should not print messages from remote

[Erik Helin]

Hi all,

please review this patch that adds `--quiet` to `git-publish` and updates
`git-pr` to make use of the `--quiet` flag. This is to prevent output from the
remote about creating a new pull request from showing up.

I also fixed a bug where the upstream branch has to be re-read after a
succesful publish.

Thanks,
Erik

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

-------------

Commits:
 - 37422af0: skara-194

Changes: https://git.openjdk.java.net/skara/pull/319/files
 Webrev: https://webrevs.openjdk.java.net/skara/319/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-194
  Stats: 35 lines in 2 files changed: 29 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/skara/pull/319.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/319/head:pull/319

PR: https://git.openjdk.java.net/skara/pull/319