Fix error handler (it wouldn't show notifications)
Disable sass source maps (it causes segfaults)
Improve error handling

* Make the error handler emit an "end" event
  (so the stream won't be stuck)

* Add gulp-plumber (https://www.npmjs.org/package/gulp-plumber)

* Add plumber to browserify helper.
* Add guzzle.src method:

     gulp.src(...).pipe(plumber())

  uses gulp-plumber to absorb error messages.
Add guzzle.pipe

* With guzzle.pipe() you can do stuff like this:

  guzzle.pipe(stream1, [stream2, [stream3], stream4], stream5)

  It makes the guzzle helpers easier to implement because I can just
  return an array of streams (instead of using event-stream.pipeline)

* guzzle.pipe() overrides the result stream's "pipe" method so it
  can will use guzzle.pipe() (so you can use it again with multiple
  streams).

* guzzle.src() now returns a guzzle.pipe version of the source stream,
  so you can do:

    guzzle.src(...).pipe(stream1, stream2)