Following configuration:

http () {
    rest () {
        vhosts = [ 'tigase.org' ]
    }
}

doesn't work with JDK based http-server (only works with Jetty)

The documentation (https://docs.tigase.net/tigase-server/master-snapshot/Administration_Guide/html/#_list_of_virtual_hosts) is not clear that it's supposed to limit requests based on Host header.

1. fix http-api based on JDK http server
2. reword the documentation to make it more explicit, e.g.: "This provides the ability to limit modules to be available only on listed hosts (i.e. Host header from HTTP request and not VHost against which the request is made), and allows to set context path to / for more than one module. Property accepts list of strings, which in the case of config.tdsl file format is list of comma separated domain names and in DSL it is written as list of strings"