RFR: 189: git-pr should detect issue from branch name

[Erik Helin]

Hi all,

please review this patch that takes the first steps towards making `git-pr` a
bit smart with regards to detecing JBS issues. This patch makes `git-pr` detect
a JBS issue from a branch name (currently only supporting the long form of
"project-id"). If a matching issue is found then the title of the PR will be
automatically set to the title of the issue.

Thanks,
Erik

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

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

Commits:
 - 0aa717ae: skara-189

Changes: https://git.openjdk.java.net/skara/pull/312/files
 Webrev: https://webrevs.openjdk.java.net/skara/312/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-189
  Stats: 31 lines in 2 files changed: 30 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/312.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/312/head:pull/312

PR: https://git.openjdk.java.net/skara/pull/312