Add localhost_ignored? to request_ignorer

[ThHareau]

In our setup, we want to use VCR in a helper, which needs to ignore localhost. At the end of the helper, we want to unignore localhost, but only if VCR was not configured to ignore localhost before.

module SomeHelper
    def action
        with_vcr do 
            call
        end
    end

    private

    def with_vcr(&block)
        localhost_already_ignored = VCR.request_ignorer.localhost_ignored?
        VCR.request_ignorer.ignore_localhost = true unless localhost_already_ignored

        VCR.use_cassette("helper_cassette") { yield block }
        VCR.request_ignorer.ignore_localhost = false unless localhost_already_ignored
    end
end

This PR adds the method localhost_ignored?.

[olleolleolle]

This is a helpful addition to this object. It wraps access to the set of ignored hosts and the constant, in a useful name. Thanks for adding this.

[ThHareau]

You are welcome :)

[olleolleolle]

Looks good to me!