userportal,webadmin: fix dtd check

In another patch we added set-property-fallback which is
not defined in the GWT dtd before 2.5. This patch sets
the DTD to 2.5 so that eclipse doesn't complain about it.
Note that the DTD version for userportal was 2.3 and
webadmin was 2.2. The build doesn't actually care about the
DTD.

Change-Id: I9523686fa7b7e005830b4f247d998fbfb01259e2
Signed-off-by: Alexander Wels <awels@redhat.com>