Added IPMI_USER_OPTIONS support to ipmi_client.robot.
Added IPMI_USER_OPTIONS support to ipmi_client.robot.

- Needed the ability to speficy additional ipmitool options (e.g. -vvv)
  to resolve product code defects.
- Also fixed coding-standards compliance violations in the
 'Run External IPMI Standard Command' keyword.
- Note: Support for IPMI_USER_OPTIONS is currently provided only in
  'Run External IPMI Standard Command' where the need arose.  Later
  changes can expand this support to other keywords.

Change-Id: I8fb0b05a03a146f48c2d99cac60066493f824a5f
Signed-off-by: Michael Walsh <10404802c7de463f402c4a18638106ca1b12ef61@us.ibm.com>

openbmc/openbmc-test-automation,openbmc/openbmc-test-automation