Add password complexity hints

[ChrisEdS]

Steps to reproduce

1. Setup password policy
2. Create a guest user
3. Set password

Expected behaviour

With this pull request we introduced password policy hints on the server side: owncloud/password_policy#335

The same behaviour should be also implemented for the guest account.

Actual behaviour

No hints will be shown when creating the guests password.

The hint is showing up one-by-one after setting a password:

[ChrisEdS]

We should then make the upper and lower case uniform right away.

vs

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