Make forbidden path test a separate function

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Clean up utilities.sos_get_command_output()

Remove dead code and clean up the logic in sos_get_command_output.
This paves the way for simplifying parameter and return passing
in the Plugin command output entry points.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Clean up sos_get_command_output() and friends

Returning a 3-tuple has always been ugly. It gets worse as the
parameter list for this family of functions grows. Worse, the 3rd
member of the tuple is unused and is always set to 0.

Rip the whole mess out and return a single, simple dictionary
object with 'status' and 'output' keys.

Update utilities_tests to reflect the new interface.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Fix tuna collection in kernelrt

The path to the 'head' binary was mangled in the automated PATH
conversion (commit e0d132e). It's not required anyway - we might
as well grab the entire output. Also remove a useless package
check before running the command.

Fixes Issue #254.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>