Add a bunch of filters support

- If the filter is a string, it will be matched as the entire domain and not
  just the beginning of the domain (it makes more sense since the gem is named
  'rack-domain')
- If the filter is a regexp, everything behaves like before
- If the filter is an array of strings and regexps, it will match if at least
  one of its element match the domain (as described above)
Write the docs in the README, bump version to v1.0.0