Add support to delete commit comment reaction

[wesleimp]

Delete a commit comment reaction

• DELETE /repos/:owner/:repo/comments/:comment_id/reactions/:reaction_id
• Docs: https://developer.github.com/v3/reactions/#delete-a-commit-comment-reaction

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[gmlewis]

Thank you, @wesleimp!

I think we should also add a new DeleteCommentReactionByRepoID method in this same PR which supports the comment in the docs that says:

Note: You can also specify a repository by repository_id using the route DELETE /repositories/:repository_id/comments/:comment_id/reactions/:reaction_id.

You can either call out to a private method where these two public methods just generate the URL and pass it to the private method that does the rest (which I personally prefer), or just have to fully complete public methods. Your choice.

[wesleimp]

Thank you, @wesleimp!

I think we should also add a new DeleteCommentReactionByRepoID method in this same PR which supports the comment in the docs that says:

Note: You can also specify a repository by repository_id using the route DELETE /repositories/:repository_id/comments/:comment_id/reactions/:reaction_id.

You can either call out to a private method where these two public methods just generate the URL and pass it to the private method that does the rest (which I personally prefer), or just have to fully complete public methods. Your choice.

@gmlewis I think now the changes are ok

[gmlewis]

Thank you, @wesleimp!
LGTM.

Please make sure to sign the Google CLA, and then we will be ready for a second LGTM before merging.

[wesleimp]

@googlebot I signed it!

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[gmlewis]

@martinssipenko - if you feel like reviewing and approving, your help would be greatly appreciated!

[martinssipenko]

LGTM

[gmlewis]

Thank you, @martinssipenko !
Merging.

[gmlewis]

Relates to: #1442.