Reliably identify a relevant sitename when configuring new sites

[jmorgannz]

This is a separate feature opened after discussion of the subject in the #68 PR.

Example domain name:

• subdomaina.subdomainb.website.com.tw

Discussion to date has yielded the following:

1. Identify the public suffix of a domain (com.tw)
2. Identify the sitename as the first domain segment left of the public suffix, including the public suffix (sitename.com.tw)
3. Ignore 0-n subdomains left of the sitename (~~subdomaina.subdomainb.~~website.com.tw)
4. In the case where it is desired to identify the sitename as a subdomain, manual override should be accepted

Methods discussed:

1. Use a limited pre-defined list of public suffixes augmented by user configurable over-rides. (#68)
2. Source and load a comprehensive list of fixed public suffixes requiring no user configuration or override.

Solution 2 has been leaned toward as a favourite by importing a copy of the Public Suffix List and a system to read / use it.