We were not searching for objectclass so the test to se if a user had the
posixAccount attribute was failing and the user was not marked as ipa_user.
This in turn caused us to not synchronize legacy hashes by not trying to store
the userPassword attribute.
Fixes: https://fedorahosted.org/freeipa/ticket/1820
Expiration time should be enforced as per policy only for users and only when a
password change occurs, ina ll other cases we should just let kadmin decide
whther it is going to set a password expiration time or just leave it empty.
In general service tickts have strong random passwords so they do not need a
password policy or expiration at all.
https://fedorahosted.org/freeipa/ticket/1839