chore: update deps

chore: update Travis CI

docs: fix lint error

docs: fix broken link

refactor: update deps

We now use `spf13/afero`

docs: add links to VS docs

Revert 'rules'

We'll do this closer to 2.0.0

chore: switch to modules

Addresses errata-ai#120.

fix: report the given (not normed) extension

test: add consistency to 'Load individual rules'