[erp5_officejs] changes to have "Javascript Editor" on official officejs.com
Make everything ready for official release of "Javascript Editor" on official officejs.com :
- update dropbox_app_key
- add icon (should be changed when a better icon is provided by Vincent or Sven)
- update the officejs export page to support codemirror
- reorder the apps on officejs appstore
- make the app a progressive webapp