ensure travis installs the right version for these [PkgVersion] options
add explicit deps on the versions of strict, warnings available in perl 5.8.3

This may seem really bizarre to do, but Modern-Open has been packaging its own
version of warnings.pm and polluting lots of cpantesters results, so this
protects against that.
silence warning: Name "main::HAS_NC_AC" used only once: possible typo at t/metaclasses/exporter_sub_names.t line 37.