removed some unused/unnecessary methods

Site

See merge request !19

Removed groovy

#80 switched to xml and removed groovy from pom.xml

See merge request !22

New stage id's

Modified the way how TeeTime names the stages. #76

See merge request !20

remodelled download page and main page

declared some stages as final;
added EveryXthPrinter;
removed logging from CollectorSink;
moved id and logger from AbstractStage to Stage