Entry filter in browse is configurable

The filter to determine which files/folders are displayed when browsing the
storage service (ie starting a transfer) is now a parameter, instead of
builtin.  Default is still to display folders but not files.
Ingest: Add metadata files structure

Add page to upload new metadata files from.
Ingest: Add metadata files javascript

Add endpoint to copy metadata files. Add JS and templates to display
the browser to select files.
METS: Cleanup handling of parsed metadata from CSVs

Clean up data to be sane before passing to helper function. Adjust
helper function parameters and return value to work better with reingest.
Support metadata files added during Ingest

refs #6488

When writing the METS, check for a metadata.csv added to the SIP,
in addition to ones from the originating transfers.  Add conversion
of metadata.json to metadata.csv for files added during ingest.

Move metadata reminder to before processing metadata directory, so new
files are processed.