Fix Handlebars/Mustache support

Handlebars and Mustache templates don't support single line comments. When grock creates docs for them, all of the code is removed from the output. Changing this one line fixes that by checking for the existence of `aSingleLine` before looking for a match.
Merge pull request #22 from missionfocus/check-for-single-line-regex

Fix Handlebars/Mustache support