Add a simple API for calibration data and search results

[jimallman]

This would be an alternative to using the website, e.g., for automatic queries by other programs like BEAST. Ideally it would use common logic for downloads and optional tabular displays on the web.

• use cases? here's some low-hanging fruit

    support existing queries
        full advanced-search w/ filters
        simplified?
        terse result (ids) or full data
    fetch a node with
        min
        max
        other info?
    fetch minor record types?
        fossil(s)
        publication(s)

• output could be JSON or "tabular" text (CSV, TSV, etc)
• read-only API to start; eventually could be used for bulk uploads(?)
• offer terse and verbose output (mimic results page vs. detail pages)
• offer download functionality (all formats?)
  - on search results page (for each, or all)
  - on individual calibration page
• LATER: start to show these in the web UI? as tabular displays
• tabular-display options for
  search results
  new data entry/edits?

[jimallman]

I'll add some more detailed issues based on recent API discussion at NESCent.