RFR: 322: Improve error message on non-author /integrate

[Robin Westberg]

Hi all,

Please review this change that gives a more helpful error message if a potential sponsor issues the /integrate command
when they probably wanted to do /sponsor.

Best regards,
Robin

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Commit messages:
 - Suggest the sponsor command if integrate is given by an eligible sponsor

Changes: https://git.openjdk.java.net/skara/pull/527/files
 Webrev: https://webrevs.openjdk.java.net/skara/527/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-322
  Stats: 60 lines in 2 files changed: 59 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/527.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/527/head:pull/527

PR: https://git.openjdk.java.net/skara/pull/527