Add Perl 5.18.2 recipe

For a project I'm working on at the moment, I need to run some legacy Perl code, and I'd like to be able to manage all of my deployment stuff through conda, so I've created a Perl recipe.

I know @tpn has created a [repository for CRAN R recipes](https://github.com/tpn/cran-conda-recipes). Maybe I will have to do the same for Perl CPAN ones. :grimacing: