Introduces HostOrIP module.

Place to put utility method(s) for converting from user-input strings of
host names or IP addresses and converting them to HostName or IPRange
objects (which properly convert to XML, when needed).
Convert site to use new HostOrIP#convert method.
Introduce global settings object.

Load and alter global settings. Currently only supporting the loading
and changing of asset exclusions. Indirectly allows for manipulation of
any other fields, but no convenience methods.