Add extra input option to determine production deploy

[gvdp]

I was running into a problem while trying to deploy my site to 'production' when the action was triggered by pushing a new tag. I noticed Issue #102 already existed which deals with the same problem, so I took a stab at implementing it. If I followed the discussion correctly the consensus was to name the input property production-deploy, if not that's an easy rename.

I also added a unit test (only for this draft boolean though, not every option) but I'm not a natural at Jest so that might require some tweaking.

I'm already using this branch in my private repo so it does work :-)

[nwtgck]

@gvdp Fantastic work!

The implementation is exactly or beyond what I want to implement. Actually, I thought I will need mock to implement this feature, but you have implemented!!

[nwtgck]

I also added a unit test (only for this draft boolean though, not every option)

I think it's good. Currently, we have following options on deploy() function. Only draft is logically decided. The others are very simply decided. Their values provided with with: or undefined if not specified.

  {
      draft: !productionDeploy,
      message: deployMessage,
      configPath: netlifyConfigPath,
      branch: alias
  }

[nwtgck]

(Security note: I built dist/index.js with npm run all locally, but I had no diff.)

I made a minor change. I'll merge this!