Add an Erasmus University domain to whitelist

This patch adds *.ihs.nl, the domain of the
Institute for Housing and Urban Development
Studies at Erasmus University Rotterdam to
our $wgCopyUploadsDomains whitelist so as to
allow mass uploads with the GWToolset tool.

Requested on Bugzilla by a Dutch special
Wikipedian-in-Residence.

Bug: 67120
Change-Id: Ie96265c4f0b560bfc6e02769e4d95066f32138c9