[CLC-2123] Directives work for html snippets

JIRA: https://jira.media.berkeley.edu/jira/browse/CLC-2123

A very good recent post on directives if others are interested: http://www.ng-newsletter.com/posts/directives.html

Likely to generate merge conflicts if the other CLC-2123 style tweaking pull is merged first. Opening pull to get @christianv 's attention.