Returns ability to set the prefix, fixes #36
Also fixes spelling mistake, fixes #35
Ignore errors when unlinking empty (or non-existing) npmrc
make underscore prefixed env-configs work

take care that environment variables like npm_config__auth
are working and you do not have to use --_auth=foo

fixes #19
Simply _env stuff, add test for same
v1.1.2
eslint suggestions
credentials: less magical, more dynamical
email is now always scoped to a registry