Google Sign-in + Drive workflow

[migueldinisdev]

• Google manual Sign in
• Google Auto sign in when entering the page and automatically retrieve the json (and initialize store)
• Sign out button
• automatically save on drive (settings)
• lock file so we avoid concurrency or another good solution
• option to convert from offline to drive (and tell user they might overwrite current data in drive)
• backup manager
• Validate App in Google Cloud