Add handling for missing updated date on whois.register.com.
Fix `ruby-whois --version`
Merge pull request #356 from micat/fix-executable-version

Fix `ruby-whois --version`
CHANGELOG for GH-356
Merge pull request #353 from Shopify/register-com-missing-update-date-problem

Add handling for missing updated date on whois.register.com.
CHANGELOG for GH-353
Release 3.5.6
Fixed conflict in version.rb and gemspec