BugFix: user name contains invalid characters

There is an typo in the policy "[a-zA-z_]" configuration.
It it should be "[a-zA-Z_]"
BTW: Group name has the same issue, fix it by the way.

Tested: Create a username contains invalid characters like: ^, [, or ].

Before: invalid character can be added as username
ipmitool user list 1
ID  Name      Callin
4   ^test     true
5   [test     true
7   ]test     true
8   _test     true

After: error will be returned once user name has invalid character.
ipmitool user set name 4 ^test4
Set User Name command failed (user 4, name ^test4): Unspecified error

UnitTest is added.

Change-Id: I86b062faea84906dde7cf37a0d51631d78526cb1
Signed-off-by: nichanghao.nch <nichanghao@linux.alibaba.com>
Signed-off-by: Kwin Wang <wangkuiying.wky@alibaba-inc.com>
2 files changed