Merge pull request #1 from pieper/master

fixes for slicer4.2
Refactor the directory structure according to the SuperBuildExtension template of 3D Slicer.
Rename SlicerVmtk4 to SlicerVmtk (by dropping the 4).
Rename qSlicerVmtk4Module to qSlicerVmtkModule.
Update the README.
Make ExperimentalUpload works now.
Replace import * statements.
Fix install rule.