Fix wallpost images
Closes #279 (closed)
What does this MR do?
- Fixes a refactoring mistake writing image paths into a wrongly named variable
- Adjusts paths in wallpost output images to be absolute, e.g. fixes wallposts on e.g. profile walls
- Minor style fixes
How confident are you it won't break things if deployed?
quite, tested locally
Links to related issues
- 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))