Echo data-deposit DOI/URL on Metadata tab.

This also adds the ability to edit this field directly, which raises
several questions about the relationship between supporting files,
imported trees, and existing data deposits; see #445.
Show data deposit DOI/URL in References page.

This restores a link that was previously removed. See #445.
Friendly TreeBASE deposit links on References page

As described in #445.
Adding reminder ("scold") about adding data.

This reminds the user (just once per session) that any file or tree data
added should already be present in the defined data deposit. If no
deposit DOI/URL has been defined, the message will not appear. See
discussion in #445.
Merge branch 'master' into editable-data-deposit-url
Merge pull request #474 from OpenTreeOfLife/editable-data-deposit-url

Editable data deposit DOI/URL, added to References page