PocoSQLDeviceDao: fix ID type for database
PocoSQLDeviceDao: fix ID type for database

The gateway and device ID should not be represented as strings because
in database, they are declared as numeric types.

Signed-off-by: Jan Viktorin <3eab6ac54c005c4408f608556a6663b7f2abede7@fit.vutbr.cz>

BeeeOn/server,BeeeOn/server,BeeeOn/server,BeeeOn/server