Mdm::Host#address IPv4 CIDR, Range, and address search

[MSP-10033](https://jira.tor.rapid7.com/secure/RapidBoard.jspa?rapidView=84&selectedIssue=MSP-10033)

Search `Mdm::Host#address` using the `address` operator, which can searching using the CIDR (address/prefix_length), Range (address-address) or single address format.
Why is this not `parent::Single.regexp` as above?