Install script for OpenBSD 5.3

Works around two issues we ran into:
1. The perl EV module requires `LD_PRELOAD=libpthread.so` e.g. `perl -e
'use EV;'` fails, but `LD_PRELOAD=libpthread.so perl -e 'use EV;'`
works.
2. OpenBSD 5.3 includes Perl 5.12 which does not include IO::Socket::IP
which is also not available in a port, so we dropped by to
IO::Socket::INET which also required changing the PeerSocket parameter
to PeerPort.
Moving install-openbsd into contrib/
Remove unnecessary PeerService PeerPort change, already in master
Merge pull request #4 from dlundquist/openbsd-5.3

OpenBSD 5.3