Add tests to compare the marshaled packets with ipmitool's output

[utkuozdemir]

Got the idea while fixing 07fafa6, I would suggest adding tests to compare the sent/received payloads of this library with ipmitools, to catch any potential incompatibilities. ipmitool -vv prints the raw payloads - it should be possible to parse the output for the comparison. Or maybe there is a better way.

[bougou]

It would be very useful to have these kinds of tests.

I'll try to do that, and PRs are welcome.