Move `coveralls` gulp task to appveyor.yml?

[VanDalkvist]

During creating new Appveyor build I faced out with issue - I could not pass a build with unit-tests gulp task because it depends on coveralls task which should be configured for appveyor build previously. I am proposing move coveralls task somewhere to be executed after unit-tests are done.

[gerich-home]

Agree, this needs to be changed. We could:

1. Move the logic of https://github.com/gerich-home/it-depends/blob/master/gulp/unit-tests.js#L26 to appveyor.yml for now
2. Add one more check to https://github.com/gerich-home/it-depends/blob/master/gulp/unit-tests.js#L26 to verify we have decrypted coveralls.yml file in the repo root.

As a bigger task we could move to gulp 4 and use the approach proposed in the end of this article: http://blog.reactandbethankful.com/posts/2015/04/23/building-with-gulp-3-and-4-part-1-examples/

[VanDalkvist]

About gulp 4. It is not released yet, as I see. https://github.com/gulpjs/gulp/releases

[gerich-home]

ah, ok. Well - then just 1 or 2. Or both at once.

[VanDalkvist]

I can do it I think

[gerich-home]

Do it! :)

[VanDalkvist]

Closed due to #62