Convention for output structure

[blahah]

dir-name
|- manifest.json # a list of files and the elements they derive from
|- fulltext.xml 
|- fulltext.pdf
|- image/
  |- fig.1.png
  |- fig.2.png
|- supplement/
  |- supp.1.csv
  |- supp.2.pdf
  |- supp.3.xslx
|- bib.json # metadata that results from scraping, in bibJSON formaet

Other files and directories will be added later by norma, ami, etc.

this is a WIP - comments welcome @petermr @rossmounce @markmacgillivray