Ensure User's Password is always String
Ensure User's Password is always String

When OpenStack User's password was a Number, fog-core coerced it to Numeric type, which caused
HTTP 400 failure leading to print requed malformed error including the password.

Value's coercing function from fog-core is a feature so should not be changed,
so adding String cast directly to OpenStack provider.

Related to https://bugzilla.redhat.com/show_bug.cgi?id=1723180

fog/fog-openstack,fog/fog-openstack