Updating print buttons to use font awesome 4.0

This is broken under 2-2-stable after @radar's sweet Font Awesome upgrade.  This *should* sort it out.

Fixes #54
Reattached @column_widths in line_items_print_box template.

Previously that @column_widths ivar was going nowhere.  Passing it to the table() block ensures that the output dimensions match the widths as set above.

Fixes #55
added syntax highlighting
Merge pull request #58 from BenMorganIO/syntax-highlighting

added syntax highlighting
Merge pull request #1 from spree-contrib/master

Update from upstream