Provide GitHub version notification

[Michionlion]

A comment or CI notification should be added to every versioned pull request in a repository with PR Tag Release enabled. This notification should indicate what the before and after version will be, as well as an example of the Release body. Perhaps some configuration or documentation links can be included as well.

Label method

• Create major, minor, and patch, labels if they don't exist (POST /repos/:owner/:repo/labels)
• Get labels on PR (GET /repos/:owner/:repo/issues/:number/labels)
• Delete old label if it changed (DELETE /repos/:owner/:repo/issues/:number/labels/:name)
• Assign relevant label (POST /repos/:owner/:repo/issues/:number/labels)