GithubStatus: Allow config to specify the integration description and context

Dependencies

• [2] WIM6VQOH GithubStatus: Include the full job name and build ID in the context.
• [3] NSRWW6LC Add a plugin to interact with the github status API.

Change contents

• replacement in src/lib/Hydra/Plugin/GithubStatus.pm at line 43
  [2.292]→[2.292:462](∅→∅)
  − description => "Hydra build #" . $b->id . " of $jobName",

  − context => "continuous-integration/hydra:" . $jobName . $contextTrailer
  [2.292]

  [2.462]
  + description => $conf->{description} // "Hydra build #" . $b->id . " of $jobName",

  + context => $conf->{context} // "continuous-integration/hydra:" . $jobName . $contextTrailer