We should follow GitHub Ruby Styleguide.
Strings section says:
Prefer double-quoted strings. Interpolation and escaped characters will always work without a delimiter change, and ' is a lot more common than " in string literals.
- bad name = 'Bozhidar'
- good name = "Bozhidar"
Whiteboard: gci2013 https://www.mediawiki.org/wiki/Google_Code-In#Candidate_tasks