Added empty sharing popup.
Almost working sharing button.
Fixed incorrectly created scopes.  Fixed link to use reader_tokens[] instead of
api_token.  Fixed to update color/text of sharing button on files page.
Fixed scope to use request.request_method (the effective request method in
rails) instead of request.method (the actual HTTP method).  Added word-wrap
style to popup.
Adding missing file.
Merge remote-tracking branch 'origin/master' into 2044-share-button
2044: Sharing link now shown in "Sharing and permissions" panel, no longer uses
a modal popup.  Produces download link that is confirmed works.
Merge branch 'master' into 2044-share-button refs #2044
Merge branch 'master' into 2044-share-button
2044: Fixed CollectionsController#search_scopes to use 'filter' correctly
instead of using 'where' incorrectly.  Reverted most changes to
ArvadosModel#ensure_owner_uuid_is_permitted.  Added rescue to
collections/show.html.erb when log.event_at is nil.
Merge branch '2044-share-button' refs #2766