chore(appveyor): disable integration tests
chore(appveyor): disable integration tests

These are currently failing on master, attempting to resolve them in
https://github.com/apiaryio/drafter/pull/673. Disabling integration
tests in interim so we're not blocking development while we fix Aruba.

apiaryio/drafter,apiaryio/drafter,apiaryio/drafter,apiaryio/drafter,apiaryio/drafter