Remove Magnific Popup by rewriting trust bananas to fancybox

This should help replacing it with some modern component at one point.

addbanana was unused since 8e7848b3

This is a part of &22 (closed).

What does this MR do?

• Removes a client-side dependency
• Rewrites frontend code to use another library
• Rewrites frontend code to be more readable
• Rewrites some backend code to be less generic, apparently from a time when rating people was possible or planned
• Removes some unused code and CSS
• Removes unused data from database and Gateway / methods

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

It would be good to have this tested, since it's never 100% certain that "unused" code was in fact unused ;-)

How to test

• open user profile
• play around with viewing and giving trust bananas
• foodsharer should not be able to see trust bananas

Screenshots (if applicable)

Checklist

• added a test, or explain why one is not needed/possible...
• 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))
• Once your MR has been merged, you are responsible to update the #foodsharing-beta Slack channel about what has been changed here. They will test your work in different browsers, roles or other settings