Merge pull request #12 from Connexions/ticket499++

refs #499: convert sections from aloha to structured html to cnxml
Merge pull request #14 from Connexions/icket493

Ticket493
Merge pull request #15 from Connexions/ticket510

section must have a nonblank @id.
refs #510: header nodes in Aloha should not have @class on input.
Merge branch 'ticket510++' into testing