Iscsi various

These patches are needed to make our iscsi code to work with update packages from CentOS 6.4.
Frediano has tested these patches in the upgraded environment while I did basic regression tests.

There patches are supposed to make the code work with current trunk version and future version.

The patch "Ignore innocuous errors from iscsiadm" can be improved in exception handling but,
because of weirdness-es of your exception layer, the patch would become either cumbersome or
much more complicated. If you have ideas, feel free to send suggestions