Add ability to send release notes using the API #428

When using the oreDeploy task in Gradle (or any other auto deploy task), it uploads the file to a channel and publishes it. However, it will do so with the default message for a file release, something like "Welcome to your project!", which will then need to be altered online after publish.

There should be an API endpoint that uses the Deploy Key to submit the release notes along with the file. This would then require updates to the oreDeploy gradle plugin, and would be of interested to @Faithcaio's maven and @Katrix-'s SBT plugins.