Validate IP address ranges correctly on Alias Bulk Import

The code was there to attempt to validate and implement IP address range lines in Alias Bulk Import e.g.
10.20.0.0-10.21.22.0
should produce a bunch of smaller ranges with appropriate CIDRs.
This fixes the code so IP address ranges actually make it through into the resulting Alias.
This fix should merge easily into 2.1 branch also.