add the logging of the body of a POST request

When analyzing POST requests, it is useful to have the body of the
request as well.
Also reformatted the stringbuffer.append() methods and added javadoc
comments.
make slowrequests feature more useful for demo and testing

* added a sample component which delays page rendering for 5 seconds;
  this allows it to demo the feature more efficiently
* default config: log complete requests into into logs/slowrequests.log

* polishing: remove some various stuff leftover from the maven-archetype