Add "Download" button to Table query pages

[wmwv]

For any page that displays a table, add a button that says "Download"

1. It's fine if that's just JSON for now.
2. "Recent Objects"
3. "Recent Alerts"
4. "SALT2" page
5. Think about whether this should be on a per-page basis or rather just some overall template update that adds a page to any such pae.