jcr2vfs: fix logging in exporter

 * excluded log4j (+ added bridge to
   slf4j)
 * sl4j + logback should be used
   for all logging
jcr2vfs: exclude bouncycastle deps from exporter
jcr2vfs: fix logging in importer

 * excluded log4j as it should not be
   needed (brought transitively by
   uberfire deps)
 * slf4j + logback should be used
   as central logging solution
jcr2vfs: include logback-clssic in -with-deps zips

 * actual logging implementation is needed at runtime,
   when running the migration. It is better to let
   the individual modules chose the version as the
   export will typically need different one as it depends
   on Drools/jBPM 5.x stuff
jcr2vfs: add proper logging into distribution
jcr2vfs: include new line char after the last message in exporter
Merge pull request #5 from psiroky/fix-logging

Multiple fixes for logging in export/import/distribution modules