Adds localizations
Introduces an image with an alternate text
Re-implements group toggle in jQuery
Hides expand/collapse all button for text reader
Adds changelog entry
Uses icon font instead of expand/collapse image
Removes superfluous locales
Merge pull request #819 from opf/fix/accessibility_alt_text_collapse_expand_on_grouped_work_package_list

[FIX] Accessibility alt text collapse expand on grouped work package list