request.env['REQUEST_URI'] does not include subdomain

Since channels and main website may be in a subdomain, the return_to
must respect the original subdomain.
Share cookies between subdomains but not with the root-level domain
Default localhost to lvh.me since support subdomains
Standardise test domain to example.com

It's the default of Capybara already.
Merge pull request #14 from neighborly/im-fix-ccf-login

Fix login inside channels