Add extra method to i18n service.
Remove useless data/event binding on i18n directive.
Remove i18n mock from wisiwyg directive.
Normalize usage of quote char to double-quote char on wisiwyg module.
Fix vendor css loading on gulpfile.

Bug introduced in gulpfile refactor.
Merge pull request #91 from taigaio/wisiwyg-and-i18n-fixes

It's ok bro :clap: :clap: