Test suite: Don't use DNS lookups

Different operating systems do behave quite differently when doing DNS
lookups, for example "127.0.0.1" sometimes resolves to "localhost" and
sometimes to "localhost.localdomain" (for example OpenBSD). And other
systems resolve "localhost" to the real host name (for example Cygwin).

So not using DNS at all makes the test site much more portable.
Merge remote-tracking branch 'alex/TestsuiteNoDNS'

* alex/TestsuiteNoDNS:
  Test suite: Don't use DNS lookups