Escape fairteiler title

Closes #409

What does this MR do?

• checked all occurences of the fairteiler name and escaped it properly
• (slightly related...) escape the title of a v_field everywhere. This has potential of breaking something, but I did not discover anything so far
• refactor some bits of fairteiler page to twig
• reuse twig fairteiler list for regions also for the fairteiler list in fairteiler module (they were similar, now they are even closer...)
• As it was a two-liner... handle fairteiler descriptions as markdown (to get rid of strip_tags and it was possible...)

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

Tested all changes in functionality manually.

Links to related issues

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))