modify dockerfile
support backend failover
update documents
support different protocl backends(tcp/udp only)
support syslog as backend
set default route id as route file name
Revert "set default route id as route file name"

This reverts commit bb37ced29a7bca9187934923d39391b8730623d8.
set route ID to route filename if ID doesn't specify
simple reload
support signal.HUP to reload lenz
update Readme