Create a separate API server app

[michwill]

New ZEO5 update breaks old API server, so we need to create a new one. Here are the design ideas:

• Use something fast and simple. Falcon framework is good?
• Should be rest, not just JSON
• Encryption keys should live with API server, it will handle security
• Should live in a separate package in zerodbext namespace
• JSON-related code in zerodb package should move here
• Optional SSL between client and API server