Nextcloud AppStore Integration

[rotdrop]

• [x] register the app in the app-store
  • [x] request app certificate
  • [x] obtain app certificate
  • [x] register app
• [x] Transifex integration
  • [x] request Transifex translation support
  • [x] receive translations from Transifex
• [x] Release the first "stable" version