Simplify package create form

[rgrp]

Sub ticket of #1294

• Initial screen just title, name, description (notes), license (and tags?).
• State that you can add data and more information on next screen. This takes you to Package 'view' where you can then do more stuff.
  • Flash some instructions? e.g. that resources are missing?
• Name slug should by default look uneditable (cf wordpress way to do the slug)

[rgrp]

This is mostly done but some final tweaks and name disabling to be done. See work in feature-1294-ux-improvements-dataset

[rgrp]

Completed with merge into default in cset:8bb0720a2150