RFR: 598: Add test-request label when test request needs approval

[Erik Helin]

Hi all,

please review this patch that adds a label for test requests.

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

Thanks,
Erik

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

Commit messages:
 - 598

Changes: https://git.openjdk.java.net/skara/pull/812/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=812&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-598
  Stats: 92 lines in 3 files changed: 91 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/812.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/812/head:pull/812

PR: https://git.openjdk.java.net/skara/pull/812