enable source maps for production builds #254

Closes #254 (closed)

What does this MR do?

enables source maps on the production builds

How confident are you it won't break things if deployed?

as much as it is possible for fs.de

Links to related issues

• #254 (closed) source maps for sentry errors

Checklist

• added a test, or explain why one is not needed/possible... (nothing to break)
• no unrelated changes
• asked someone for a code review
• joined #foodsharing-beta channel at https://slackin.yunity.org
• added an entry to CHANGELOG.md (description, merge request link, username(s))