Separate ALLOWED_HOSTS and ServerAlias configuration

In some cases it is required to be possible to have different values
of parameter ALLOWED_HOSTS in settings_local.py and ServerAlias directives
in vhost.conf. This patch separated parameter $fqdn to two new parameters:
$allowed_hosts and $server_aliases.

Change-Id: I431ec01dd32e5e7c460251502dbd1c1b03ec2fe7