Preprints - Links to external supplementary files

[mauromsl]

Is your feature request related to a problem? Please describe.
The preprint system should allow authors to add externaly hosted supplementary files (e.g.: Driad)

Describe the solution you'd like
An interface for adding a link to an external supplementary file that is then related to the submission

Additional context
Not sure if we would need versioning support here.

[tingletech]

I'll take a look at this one

[ajrbyers]

@tingletech can I get an update on progress with this?

[tingletech]

sorry, there is not really an update, I started over on this once and got about this far

+class PreprintSupplementaryFile(models.Model):
+    preprint = models.ForeignKey(Preprint)
+    url = models.URLField()
+    order = models.PositiveIntegerField(default=0)
+
+    def __str__(self):
+        return '{url} linked to {preprint}'.format(
+            author=self.url,
+            preprint=self.preprint.title,
+        )
+

+class PreprintSupplementaryFileForm(forms.ModelForm):
+    class Meta:
+        model = models.PreprintSupplementaryFile
+        fields = (
+            'url',
+        )
+
+    def __init__(self, *args, **kwargs):
+        user = kwargs.pop('user','')
+        super(DocumentForm, self).__init__(*args, **kwargs)
+        self.fields['user_defined_code']=forms.ModelChoiceField(queryset=UserDefinedCode.objects.filter(owner=user))
+
+
+

and I found the template where we could put it and the view that uses the template.

I've been working on DNS and certbot, and I just got that going last night, so I was hoping to have some time to start over on it this afternoon if nothing unexpected comes up.

[ajrbyers]

What remains on #1789 to finish this?

[tingletech]

/repository/dashboard/1010/ pages
views.repository_author_article
admin/repository/author_article.html

---

/repository/manager/1010/ pages
views.repository_manager_article
admin/repository/article.html

^^ should be able to add / remove from this page