Use centralized function/objects for all network access  #591

The network calls are scattered in many places and this is problem.

• this is technical debt
• we cannot log things easily Implement structured logging #590
• we should disable etags but this is in many places Disable Etag #321
• we cannot easily add proxy support at once Support for http/socks proxy #559
• we cannot implement API politeness at once Be polite to APIs #506 nginx import -> Name or service not known #568