RFR: 117: Add support for custom headers in notifier emails

[Robin Westberg]

Hi all,

Please review this change that adds support for setting custom headers in emails sent by the notifier.

Best regards,
Robin

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Commits:
 - f8140181: Add support for custom headers in notifier emails

Changes: https://git.openjdk.java.net/skara/pull/186/files
 Webrev: https://webrevs.openjdk.java.net/skara/186/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-117
  Stats: 33 lines in 3 files changed: 25 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/skara/pull/186.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/186/head:pull/186

PR: https://git.openjdk.java.net/skara/pull/186