Correctly set public_bind_host and admin_bind_host

Now that the bind_host setting has been split into public_bind_host and
admin_bind_host, we can use the correct attributes since we already had
this split in our attributes.

Note that, by default, it doesn't change anything as 0.0.0.0 is the
default values for both attributes.
Merge pull request #231 from vuntz/fix-bind-hosts

Correctly set public_bind_host and admin_bind_host