Use `request.remote_ip` to get remote IP

`request.remote_ip` returns a remote ip address that is "probably"
correct. It also checks if the app is getting IP Spoofing attack. It
can't protect the app against the attack perfectly, but it's better
than not having any protections.

When `request.env['REMOTE_ADDR']` gives the correct IP address,
`request.remote_ip` also returns the same. This means
`ip_whitelisted_request_proxied` looks no longer needed, but setting
it to false eliminates the use of `request.remote_ip` so it is still
good.

For more about how `request.remote_ip` calculates ip, have a looks at:
  http://api.rubyonrails.org/classes/ActionDispatch/RemoteIp/GetIp.html#method-i-calculate_ip
  (ActionDispatch::RemoteIp::GetIp is what is used inside `request.remote_ip`)

For more about IP Spoofing attack against Rails, have a look at:
  http://blog.gingerlime.com/2012/rails-ip-spoofing-vulnerabilities-and-protection/
I would like to have 'did you mean?' experience also in test env