remove gulp-util

[simonmulser]

https://medium.com/gulpjs/gulp-util-ca3b1f9f9ac5

remove gulp-util using the following API replacements:

gutil.File => https://www.npmjs.com/package/vinyl
gutil.replaceExtension => The .extname property on Vinyl objects or https://www.npmjs.com/package/replace-ext
gutil.colors => https://www.npmjs.com/package/ansi-colors
gutil.date => https://www.npmjs.com/package/date-format
gutil.log => https://www.npmjs.com/package/fancy-log
gutil.template => https://www.npmjs.com/package/lodash.template
gutil.env => https://www.npmjs.com/package/minimist
gutil.beep => https://www.npmjs.com/package/beeper
gutil.noop => https://www.npmjs.com/package/through2
gutil.isStream => Use the .isStream() method on Vinyl objects
gutil.isBuffer => Use the .isBuffer() method on Vinyl objects
gutil.isNull => Use the .isNull() method on Vinyl objects
gutil.linefeed => Use the string '\n' in your code
gutil.combine => https://www.npmjs.com/package/multipipe
gutil.buffer => https://www.npmjs.com/package/list-stream
gutil.PluginError => https://www.npmjs.com/package/plugin-error

[mdawaffe]

It looks like this was fixed in #10, but the new version was never published on npm.