long response crashes raw command

**Reported by:** [vmauery](https://github.com/vmauery)
**Original Ticket:** [ipmitool/bugs/497](https://sourceforge.net/p/ipmitool/bugs/497)

I am trying to run a raw command against a BMC that returns ~3kB of data. This crashes ipmitool. Upon inspection of the code, it is clearly a buffer overrun due to the max buffer allocated by raw being 256.