Merge pull request #50 from aroraumang/feature/task-5736

Create a new user group and send order emails to it #5736
Added checkout sign_in form as class attribute

Added sign_in form in checkout as class attribute. Downstream modules
can change the behaviour of sign_in form.
Merge pull request #52 from tarunbhardwaj/develop

Added checkout sign_in form as class attribute
Added formatLang when rendering email template #5736