this allows zip files in the import upload form
plain files are still uploaded to the selected collection but zip
contents are considered drafts with the exception of subdirectories,
these are added to the corresponding collections. if no collection is
found then it will be created.
this adds basic support for importing files as blog posts.
.txt and .md are supported at this time and the
collection is selectable, defaulting to draft.
if a collection is specified the post is federated.
