added passing test and done_testing to stop test failure

Install from CPAN was failing using Test::More 1.001006, Perl 5.16.3, Fedora 17:

    $ prove -l t/03_badhost.t 
    t/03_badhost.t .. No subtests run 

    Test Summary Report
    -------------------
    t/03_badhost.t (Wstat: 0 Tests: 0 Failed: 0)
      Parse errors: No plan found in TAP output
    Files=1, Tests=0,  0 wallclock secs ( 0.02 usr  0.00 sys +  0.01 cusr  0.00 csys =  0.03 CPU)
    Result: FAIL