* Updating valid domain registration
Prior to this commit, our regular expression did not account for the `-`
character as valid within the domain. The `-` character cannot be the
first nor last character of the domain (e.g. `-hello.com` nor
`hello-.com` are invalid but `hell-o.com` is valid).
In addition I tidied up the default value of the
`blocked_registration_email_domains` to match it's sibling `allowed_registration_email_domains`.
This relates to the spammer seo-hunt.com
* Adding validator domain validator spec
* Moving request spec to unit spec
This change does two things:
1) Allows for 2 character domains
2) Moves the spec for 2 character domains from an expensive spec to a
cheaper to run spec (e.g., request-cycle to unit-test validator)
It preserves PR #12268
