Redo gulp build for noctua core clients

[kltm]

Over time, the original gulp build pipeline for noctua apps has accumulated a lot of cruft and special cases. We need to revisit the build pipeline, simplifying where we can (less/sass, asset locations, etc.) and making the process more transparent.

This will also touch on what's going on with #260 .

[vanaukenk]

@kltm - do you want to leave this ticket open?

[kltm]

This may be relevant for https://github.com/berkeleybop/bbop-js/issues/39 and possibly "fixable" with work from https://github.com/geneontology/amigo/issues/650

[tmushayahama]

@kltm we need to not use gulp anymore.