Drop dependency on deprecated gulp-util

[TheDancingCode]

Closes #54

[demurgos]

Looks good.

@tracker1 Could we have this merged and published?

[demurgos]

Thanks!

[tracker1]

@TheDancingCode Would you like to be added to the contributors in the package.json?

@demurgos If you'd like, I could add you as a contributor so you can push to the project.

[demurgos]

I'll be upfront that being able to perform these sort of maintenance updates when there are some ecosystem-wide change would be good but I will most likely won't have time to deal with issues specific to this library (fixing CI, updating deps is fine, but not sure about issues regarding the features of the lib).
It may be helpful occasionally so if it's fine with you, you can add me.

[tracker1]

demurgos, you've been added...

after a merge...

npm version (patch|minor|major) git push git push --tags 

travis should do the publish to npm... though it was a bit wonky yesterday.

[tracker1]

I'm frankly not even using gulp anymore, mostly webpack and/or npm scripts for a few years, so I get what you're saying. I don't think there's really a need to add new features, most changes are because of API changes.

[demurgos]

Ok, thanks for the invite.