Return ability to use custom loggers and to set loggers for a specific route

[Satbek]

Closes #106

This pr almost completely reproduces #77, but added additional case handling:

If

server.options.log_requests == false
server.options.log_errors == false

and

route_options.log_requests == true
route_options.log_errors == true

then route would use log.info for requests logging and log.error for errors logging.