kie-server: require BASIC authentication by default

 * the jboss-web.xml is needed for EAP and WildFly.
   Tomcats does not need any specific descriptor,
   authentication will be done by default using
   the tomcat-users.xml in tomcat distribution.

 * descriptors for WebSphere and Weblogic
   (if needed) need to be yet created
kie-server: setup and use auth. in tests
kie-server: don't use deprecated DefaultHttpClient
kie-server: clarify usage of flag in base test class