user-accounts: add positive confirmation to the password dialog

Add checkmarks, remove exclam icons, remove tooltips, change
password hints and decrese timeout (by design).

https://bugzilla.gnome.org/show_bug.cgi?id=702476
user-accounts: add positive confirmation to the add user dialog

Add checkmarks, remove exclam icons and decrese timeout (by design).

https://bugzilla.gnome.org/show_bug.cgi?id=702476
user-accounts: Don't disable the verify password entry

This completely breaks pressing <TAB> to get to the next
control in the dialog, especially when immediately typing
a password.

https://bugzilla.gnome.org/show_bug.cgi?id=702476
user-accounts: activates_default = TRUE on add account password entries

https://bugzilla.gnome.org/show_bug.cgi?id=702476
user-accounts: Validate dialog immediately when enter is pressed

This allows users to touch type passwords, press <ENTER> without
waiting for the pasword timeout to clear.

https://bugzilla.gnome.org/show_bug.cgi?id=702476