v3.0.0

• Rework the server/client API to be more REST
• Cache available packages list in temp directory
• Improve greatly the coverage for the server extension
• JupyterLab extension only:
  • Allow the user to change the proposed environment when creating one from scratch
  • Add signals to handle environnements and packages changes (see labextension\src_tests_\services.spec.ts)
  • Improve the UI reactivity by using react-virtualized for the packages list
  • Improve the look and feel
  • Allow to choose the version to install
• Available packages truncation has been removed.