Persistency, options, username validation, project blocking

[GarboMuffin]

The goal is to make it so when people ask how to run their own cloud variable server, we have exactly one place for them to visit.

• Added option to enable sqlite-based variable persistency
• Merged option to enable username validation (username-validate-prod uplift)
• Merged project blocking mechanism (username-validate-prod uplift)
• Added option to allow non-number values
• Added a lot more options in general
• TODO: graceful database save on eg. ctrl+c
• TODO: cleanup
• TODO: update README

[GarboMuffin]

Quick update on this: I believe the current cloud-server base to be a technical dead end. Much more radical change is necessary to get this to scale to the level of traffic we have (much higher priority), so things like this are on hold for the forseeable future.

[zaid1442011]

@GarboMuffin Any updates on this? I tried it and it works fine.