Update libnet to CPAN version 3.04

  [DELTA]

3.04 2014-11-29

    - SNI is now only used for SSL connections if it is supported by
      IO::Socket::SSL (i.e. OpenSSL version >= 1).  (The previous release
      switched to using SNI by default, which caused some CPAN Testers
      failures.)  [Steffen Ullrich, PR#10]