Added Device::Modbus::Unit and a test file; fixed bugs in examples/server_rtu.pl and server_tcp
Added a couple of tests to units.t
Added Device::Modbus::Unit::Address and modified Device::Modbus::Unit to work with it
Modified Device::Modbus::Server to work with new Unit and Address modules
Device::Modbus::Server was re-writen to work with Modbus::Unit
Added tests for Modbus::Server and modified Server to work with the new Modbus::Unit
Added tests for generic server exceptions
Added one more test to serving_exceptions.t
Changed Device::Modbus::Server into a Moo::Role instead, to avoid multiple inheritance in Device::Modbus::Server::TCP.