Merge pull request #170 from nilshartmann/master

Stage View: Use Artifact-Model in Tree by using a (modified) ArtifactTreeContentProvider
Merge pull request #171 from nilshartmann/master

Stage View: Fixed 'Remove from Stage' action
Fix order of contributors in New Project Content Provider Wizard
Reverted config changes due to database problems (_contentId on Resource
was null after re-reading the db)
Introduced ZipFileCache
New UI-Action: Create a Module from selected package and resource
artifacts