Some improvements to parsing cmd output in list_
Some improvements to parsing cmd output in list_

* Properly ignore "header" lines which indicate output in "CHS" or "CYL"
* Raise salt.exceptions.CommandExecutionError on unexpected parsing
	failures
* Always check for correct len of cols array before unpacking by index

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt