node should not accept connection when cannot serve request #166
Description
Node should drop connection with an error when it is not able to serve the request. Currently, connection is always established. Client waits for response until server (node) will respond.
For example when node is syncronizing it accepts connections, but does not respond until syncronization ends. It can take few hours and TCP port is still occupied. When syncronization ends node enters read only mode. All requests are rejected. Then after a while node enters read/write mode and handles requests.