Add stub for Network component

[epicfailname]

Returns "Hello World" for any given String URL

[thomastanck]

lgtm

[rlrh]

Eventually, we will need a method that returns an InputStream, because the Rome library doesn't accept a String but needs an InputStream that can be read by an XmlReader in order to build a SyndFeed.

Refer to:
rometools/rome#276
https://hc.apache.org/httpcomponents-client-ga/quickstart.html
https://hc.apache.org/httpcomponents-core-ga/httpcore/apidocs/org/apache/http/util/EntityUtils.html

Here is a code fragment for future reference:

HttpEntity getEntity(String url) {
  CloseableHttpClient httpclient = HttpClients.createDefault();
  HttpGet httpGet = new HttpGet(url);
  CloseableHttpResponse response = httpclient.execute(httpGet);
  HttpEntity entity = response.getEntity();
  return entity;
}
entity.getContent() // returns InputStream
EntityUtils.toString(entity) // returns String