RFR: 2088: Skara /reviewers command is no longer effective [v2]

[Erik Duveblad]

> Hi all,
> 
> please review this fix for [SKARA-2088](https://bugs.openjdk.org/browse/SKARA-2088). The fix consists of adding a special value (`disable`) to the key `minimum` in the `[checks "reviewers"]` subsection. This way the functionality enabled by the `minimum` key can be disabled by `AdditionalConfiguration.java` (since INI doesn't feature a way for keys to be unset).
> 
> I also made the `ReviewersCheckConfiguration` a bit more strict - the `minimum` key should never be combined with the keys `lead`, `reviewers`, `committers`, `authors` or `contributors`.
> 
> Finally I added tests for the above three scenarios.
> 
> Thanks,
> Erik

Erik Duveblad has updated the pull request incrementally with one additional commit since the last revision:

  remove import

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

Changes:
  - all: https://git.openjdk.org/skara/pull/1581/files
  - new: https://git.openjdk.org/skara/pull/1581/files/f7e49b61..5e46899e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1581&range=01
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1581&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/skara/pull/1581.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1581/head:pull/1581

PR: https://git.openjdk.org/skara/pull/1581