Trigger binary creation when tags are created manually

[arunasank]

Fixes #258

I created a fresh "prerelease" version (4.7.2-0), and saw that the build was successful. To reproduce the error:

• I set the sha variable on https://github.com/mapbox/ecs-watchbot/blob/master/bin/watchbot-binary-generator.js#L17 to 4506f753e0955ee3683e8c396cdeea58e4442c5e
• This caused the same error to be thrown

On adding more debugging, I found that the error is thrown when we create tags manually using git tag -m .... because these tags look like 4.7.0, whereas the ones created using the npm version... command look like v4.7.0.

I've modified the regex to allow numeric tags that are created manually as well, but strongly recommend creating tags using npm version <patch|minor|major|prerelease>.

Thanks for creating https://github.com/mapbox/ecs-watchbot/pull/256/files @freenerd - it should help clarify a lot of this. 🙂

cc/ @mapbox/platform-engine-room

[jakepruitt]

For consistency, should we add a v if it's missing before writing it to S3?

[arunasank]

For consistency, should we add a v if it's missing before writing it to S3?

I think this would be confusing, since the S3 path to upload the binaries to, is conceived using the tags present on GitHub, and if we are changing the naming of these tags, we're modifying them to be different from the actual GitHub tag. I think we should use the exact same tag string on GitHub.