* [modbus] More strict nullness. Remove apache.commons.lang from itests * [modbus] Defaults for tcp and serial things according to docs * [modbus] further explicit defaults * [modbus] document default encoding for serial. RTU is pretty much the only one used in the field. Previous default was ascii implicitly. * [modbus] verify defaults are used for undefined configuration parameters Signed-off-by: Sami Salonen <ssalonen@gmail.com>