Allow user to set password to default hash

The passwd field in the output from shadow.info was normalized in
508d816 and 6239136 to make it easier for states to manage users, but
this prevents users from setting the password to the default password
hash. This commit fixes that regression.
docstring grammar fix
Rename 'pwd' field in windows shadow.info output

This makes the field name consistent with the other shadow modules. Note
that the passwd field is not used at all in Windows user management, so
this is merely a cosmetic change.
Merge pull request #6091 from terminalmage/issue6085

Allow user to set password to default hash