Fix Ajax "same origin policy" issue when port != 80 by using window.location.host

If the web server configuration is using a port different than 80, i.e. node['kibana']['webserver_port'] != 80 than we must also make sure that kibana will send the AJAX requests (_search, _aliases ...) to the same host:port, else the AJAX request will not be allowed to pass throw [1].

[1]: https://en.wikipedia.org/wiki/Same_origin_policy#Origin_determination_rules