* remove "always-include-main" test case
It was testing for incorrect behavior that has now been fixed.
See: https://github.com/zeit/now-cli/pull/464
* remove "files" array from `main` related test cases
Makes these three tests pass once again.
* always run a test for "pack-now" even when not in CI
Otherwise `ava` fails because the test did not
run any assertions.
* fix non-determinism in tests
* if `.dockerignore` doesn't exist, use `.gitignore`
* add back duplicate dei
* Move comment to appropriate line
* also check for exactly two duplicates