Rename `CACHE_DIRECTORY ` from `.erb-lint-cache` to `.erb_lint_cache`?

[joshuapinter]

I see you've standardized on using erb_lint instead of erb-lint or erblint - that's great and much appreciated.

Do we want to also rename the CACHE_DIRECTORY from .erb-lint-cache to .erb_lint_cache?

[etiennebarrie]

Yes I think that was an oversight. We'd welcome your contribution. Thanks!

[joshuapinter]

You got it. See #380.