TODO:

* Google Photo:

 ++ Port to O2:
    - updatePhoto(...) when Google Photo API supports that functionality (not yet in v1)
    - Prevent limit of API for uploading (mediaItems:batchCreate) : 50 items by default
    
    !!!!! Upload now only works with albums created by digiKam -> it's normal
    !!!!! Downloaded images won't show in digiKam view
    
    
    
 ++ Factorization: 
    - Option to choose which images to import
    - Option to choose size for image downloaded (by GPhoto Import)
    - Like in Flickr 
        -> Button Change Account only add new user accounts
        -> Button Remove Account (or Logout) really removes an account
        -> A combo box to choose account at login if user has many accounts
    - Instead of open browser for login with QDesktopServices::openUrl(url) (which is slow and leaves an unpleasant tab 
      when finishing login), maybe we should use QWebEnginePage (?)
    - Performance Improvement 
        -> Using gzip
        -> Filter API's responses 
        
        
 ++ Metadata add/removal before (even after) uploading: 
    - Reference : https://developers.google.com/photos/library/guides/add-enrichments 
 
 
