allow overwrite in the DefaultValuesTransformer
Merge pull request #32 from fieg/default-values-transformer-overwrite

allow overwrite in the DefaultValuesTransformer
fixed duplicate import events
Merge pull request #34 from fieg/import-events-fix

fixed duplicate import events (fixes #33)
minor fixes
Merge pull request #36 from fieg/minor-fixes

minor fixes
now using ProgressAwareInterface for displaying a progress bar
Merge pull request #37 from fieg/feeder-progress-aware

now using ProgressAwareInterface for displaying a progress bar