Add epoc= method to the Package base class.
Add epoc= method to the Package base class.

Should fix #51.

ryansch/fpm-cookery,cas-ei/fpm-cookery,glensc/fpm-cookery,cas-ei/fpm-cookery,kisoku/fpm-cookery,kisoku/fpm-cookery,glensc/fpm-cookery,devkid/fpm-cookery,devkid/fpm-cookery,ryansch/fpm-cookery