refs #493: exercise/solution now converts
Merge pull request #18 from Connexions/ticket519

Ticket519
Merge branch 'master' into ticket493++

Conflicts:
	rhaptos/cnxmlutils/xsl/aloha-to-html5-pass03-nested-headers.xsl
Merge pull request #16 from Connexions/ticket493++

refs #493: exercise/solution now converts
refs #499: random @data-* on header nodes must convert from aloha to structured html