Closes #6 - Output grepable support

[codingo]

This adds output grepable. I'm still unsure of its utility since likely matches isn't easy to display in this format, open to suggestions?

At present I'm just writing out:

    def output_grepable_detail(self):
        for host in self.scanner.hosts:
            output += "\n{}\t{}\t{}".format(
                str(host.hostname),
                str(host.response_code),
                str(host.hash)
            )

        return output

Likely has some use, but merits further thought. We could merge this for now and amend as better use cases for it become more known.