Don’t trust JavaScript with your dates.

Thirteen years past y2k, and JavaScript is still dumb about years less than 100 :-/

See #130
Add API spec for date handling.
Better API date handling

 * Pretty fractional second rendering
 * Fix microsecond truncation
 * Always render in UTC rather than local time
Fix Bootstrap submodule.
Bump version for 2.3.8
Merge branch 'hotfix/2.3.8'