Make table headers sticky in EARL reports

[gkellogg]

From @scor on December 31, 2012 20:42

This would help digest the new total percentage of PASS for example, and in general while scrolling the long tables.

A few jQuery libraries are available, though I haven't tested any:

• https://github.com/jmosbech/StickyTableHeaders
• http://css-tricks.com/persistent-headers/
• https://github.com/markmalek/Fixed-Header-Table
• https://github.com/benjaminleouzon/tablefixedheader

Copied from original issue: rdfa/rdfa-website#19