DLTP-186: Render formatted text attributes

Run plain-text attributes through a Markdown processor and sanitize the
output before it is inserted into a template.

First pass at implementation using RDiscount

Protect against script injection

Make quotation marks fancy

Remove untested class method

Moving utility classes to lib

Text parsing helper method and placeholder test

Adjusting rendering of abstracts; placeholder test

Tidying up tile formatting

Token test for #richly_formatted_text helper

Tests for #curation_concern_attribute_to_html

Allow setting a custom class for descriptive text blocks

Updating expected markup for edit view test

Use #public_send in lieu of #send

Adding back ETD abstract attribute rendering

Make text formatting a module function

Update helper method with new parser interface
Change Help button Functionality

Change the Help button to a dropdown menu that contains a link to FAQs:
a page that is to be written later, and Request Help which provides the
previous action of the help button, launching a modal help window.

The help button/dropdown menu has also been made available when a user
is not logged in.

dltp-174#
dltp-170#

Button Alignment

Align dropdown for Help! to the right edge of the button so that it does
not overflow off the page. From DBH feedback.

Correct URL on line 8 from collections_path to new_help_request_path.
DLTP-189 Working on UI experience when curation concern encounter generic file without content

UI changes related to empty content on generic file

Adding missing file icon
changing edit and show page of generic file when content is empty

adding spec for empty content

DLTP-189 Wordsmith as part review with Chris

Change button name on edit page when empty file found
Change Thumbnail icon on the generic file with empty content
Disable download and Rollback button in case empty content found

Fixing failed spec