Consolidate and Refactor creation/instantiation of URLs/InternetDomainName objects used by PageScanner class

PageScanner has multiple operations that require a fully-validated URL/IDN object in order to perform domain/sub-domain searching and matching. As usage has increased with the increase of report variables, some duplicated code and/or repetitve operations have made it's way into the PageScanner class. Some refactoring is needed to "pre-generate" lists of valid URLs/IDNs prior to scanning so that they are processed once at the start and available for all methods to operate on. This activity will coincide with the performance enhancements user story in pivotal.