0.22.4

See release notes of 0.22.1 for breaking changes and upgrade instructions.

• Fix install.sh not compiling locale messages (fixes #965)
• Moved trek completeness fields to setting TREK_COMPLETENESS_FIELDS. Duration
  and difficulty were added, arrival was removed (fixes #967)
• Fix regression about source locale messages (fixes #970)
• Fix regression link Back to application lost from adminsite (fixes #971)
• Serve uploaded files as attachments (fixes #972)
• Remove help texts being shown from filter forms (fixes #966)
• Fix form pills for translated languages (fixes #968)