post a comment when the 'comment' param exists

[fmy]

Like other CI tools, posting a comment into the pull request.

• new param is added: comment which is the file path of the comment message.
  • if this param is passed, try to post a comment with file content.
• this comment is posted by the user who owns the access_token.

[jtarchie]

Thanks for the PR. This is an interesting request.

The statuses on the SHA already return success, failure, etc. The follow up meta comment can be confusing as it is not directly tied to a SHA.

Are you able to give me a use case of why this would be useful? Maybe link to another CI system that does this.

Thanks,

JT

[fmy]

@jtarchie My pipeline is creating app instances for testing just after pull request is coming.
In my case, concourse notifies this testing app URLs to the pull request.

And some other use cases listed below

• post test report URLs.
• post whether test coverage percentage becomes up or down.
• post error summaries of test results.

[jtarchie]

@fmy, I like it. I'm currently doing a bit of rewrite, to make it easier to test. I'll pull this in and backport some tests.

[jtarchie]

I did merge in your commits. I just did a rebase so this PR does not reflect the updated SHAs.

Thanks for the PR

[fmy]

Thanks!