RFR: 610: Add support for other issue tracker email addresses than @openjdk.org

[Robin Westberg]

It should be possible to find Jira users based on committer email addresses that are written as `@openjdk.org` in case
they exist.

Best regards,
Robin

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

Commit messages:
 - Allow finding jira users by email

Changes: https://git.openjdk.java.net/skara/pull/802/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=802&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-610
  Stats: 95 lines in 6 files changed: 93 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/802.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/802/head:pull/802

PR: https://git.openjdk.java.net/skara/pull/802