[core] Add Feedback label for demo

Added on the right hand side with link to team@gethue.com
HUE-1801 [fb] Introduce pages with scroll when viewing a file

Introduced the concept of pages
Scroll + stream for smaller text files
Range of pages for bigger text and all binary files
[core] Move welcome tour to home

Hide the modal as it was blocking the middle top of the screen.
Only propose tours if they are available.
[oozie] Import workflow imports mkdirs and touchsz as lists of dictionaries

Instead of list of strings
[jobsub] Add description to 'get_design' call

Fixes bug where editing a design removes the description.