RFR: 637: PR author should be able to use /csr PR command

[Erik Helin]

Hi all,

please review this patch that allows pull request authors that are *not* Reviewers to use the `/csr` command. A person
who is not a Reviewer should still be allowed to state that a CSR is required (but not that state that a CSR is *not*
required).

Testing:
- [x] `make test` passes on Linux x64
- [x] Added a new unit test

Thanks,
Erik

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Commit messages:
 - 637

Changes: https://git.openjdk.java.net/skara/pull/821/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=821&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-637
  Stats: 29 lines in 2 files changed: 19 ins; 3 del; 7 mod
  Patch: https://git.openjdk.java.net/skara/pull/821.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/821/head:pull/821

PR: https://git.openjdk.java.net/skara/pull/821