js/download: Remove unwanted columns

Remove:

  1. Full text + Abstract only links
  2. Species Taxonomy link
  3. FASTA sequence
  4. Notes

Issue #333.
js/download: Filter unwanted columns from records

Issue #333.
download: Strip out XML format features

Supporting this alternative file format is extra work, and it provides
no practical benefit over the already tested and existing JSON encoding.
Merge branch 'feature/no-xml' into issue/333
js/download: Fix double dots in file extensions

Transforms 'results..json' into 'results.json'.

Issue #280.
Merge branch 'issue/280' into issue/333
js/download: Set default format type
js/download: Don't include "undefined" in CSV
js/download: Comma separated values, not tab

Issue #331.
Merge branch 'issue/331'