[Feature request] Load fixtures in subdirectories / glob support

[glen-84]

It doesn't seem to be possible to load all fixtures within the specified directory and all subdirectories. I would like to have a structure like this:

• fixtures
  • editorial
    • article.yml
    • category.yml
  • users
    • user.yml
    • user-profile.yml

etc.

A recursive option could work, but I think that supporting globs would be a lot more flexible, f.e.:

fixtures ./data/fixtures/sample/*/*.yml