get_user_info blank userid to get all users
get_user_info blank userid to get all users

If userid is blank, this function will return a list of dictionaries.
Each list entry represents one userid record.

Change-Id: I405de2f82df9dd1482964ce2772825e045154986
Signed-off-by: Michael Walsh <10404802c7de463f402c4a18638106ca1b12ef61@us.ibm.com>

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