RFR: Implement basic support for the Jira issue tracker

[Robin Westberg]

Hi all,

Please review this change that introduces a basic implementation of the Issue* interfaces with support for the Jira tracker. The implementation can currently only perform simple read-only operations, but it is enough to be used for such things as the pull request status bot.

Best regards,
Robin

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

Commits:
 - c1f4fd24: Implement basic support for the Jira issue tracker

Changes: https://git.openjdk.java.net/skara/pull/176/files
 Webrev: https://webrevs.openjdk.java.net/skara/176/webrev.00
  Stats: 335 lines in 6 files changed: 327 ins; 2 del; 6 mod
  Patch: https://git.openjdk.java.net/skara/pull/176.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/176/head:pull/176

PR: https://git.openjdk.java.net/skara/pull/176