multi-language support

Currently response strings are hardcoded, so creating a project for non-English users requires to carefully search and replace all user facing text.

At least having all text strings centralized in a single location would make this task much easier and less error prone.

Side note: Let me know what is the best way for me to contribute with suggestions like this. Maybe a Product Pains page would be a better option as not to clutter the issues page with these enhancement requests.