Add JSON-RPC client and server

[yitzchak]

• [x] Standardize API (use file uri)
  • [x] Documentation
• [x] Add BuilderCache implementation
  • [ ] Specs
• [x] Add server
  • [x] Specs
• [x] Add client
  • [x] Specs
• [x] Add common types
  • [x] Specs