Cewolf Code

added useJFreeChartMapGenerator to ChartMapTag, so it can use
the jfreechart provided map rendering instead of ours.
Useful in complex cases, when the map will contain customized elements.

fixed tutorial url

gnujaxp dependency removed

classpath is up to the same version used in cewolf project

some cleanup in exceptions,using cause-exception-chain, so hopefully no more stack trace is hidden.
also removed printstacktrace()-s and improved log quality.

fixed missing junit dependency in pom

refactor of LongTermSessionStorage, so it will use a single thread for cleanup
instead of one thread per session was used earlier

refactor of chart factory and combined/overlaid plot factory,
to fully use factories, and easy to add a new factory for simple/complex charts

refactor of chart factory and combined/overlaid plot factory,
to fully use factories, and easy to add a new factory for simple/complex charts

svg example added