DS-1945 New override property request.item.helpdesk.override to have all email requests sent to the helpdesk instead of the item submitter
DS-1945 refactor to move code into dspace-api
Add RequestItemHelpdeskStrategy, that can be enabled with Spring DI

Cleans up Sam's "hard coded" approach
DS-1945 RequestItem Helpdesk has options to contact requester, and author
DS-1945 Add request_message to requestitem DB table

Also, refactored requestitem to be a dspace-api "model", moved all DB logic
from XMLUI regarding this module to the dspace-api model.

Add the requestitem.request_message to display in the contact-author form,
so they can see what the original request message was.
DS-1945 Add license headers for requestitem changes
Restricted Item request form, add link to login page for members
For request-item move the you can login Button before the request item para
DS-740 Allow media filter to set public-read permissions on thumbnails
DS-740 default the public thumbnails of restricted objects to off
DS-2091 Upgrade HttpComponents to 4.3.5
DS-2091 Wee code change resulting from HttpComponents upgrade
Merge pull request #530 from peterdietz/DS-1945-requestitem-helpdesk

DS-1945 RequestItem to have Helpdesk be contacted instead of author
Merge pull request #543 from peterdietz/DS-740-public-thumbnails

DS-740 Public derivative thumbnails of restricted original bitstreams
Merge pull request #596 from robintaylor/DS-2091

DS-2091 Upgrade HttpComponents to 4.3.5