Bugfix/drive sync cache

[luigimannoni]

Fixes Google Drive sync cache on realtime.js while using the index-multi.html version of the checklist.
Compares the file version (apparently it's the revision version) between the "cached" response from Google Drive with the current file list already fetched.

Steps to replicate the bug in the current drive-realtime-deprecation branch:

• Create a new project
• Rename it "project1"
• Tick some boxes
• Create a new project from the sidebar
• Rename it "project2"
• Tick some boxes
• Switch back to "project1", everything should work
• Switch back to "project2", now the "project2" doesn't have any boxes checked.

@sovesove good if you can try on your end with Safari as I don't have that on my Linux

[sovesove]

I trust you @luigimannoni 😂