Parameterize Revit version in project files.

This will allow us to switch the Revit output paths with one change in
our CS.props file.

Conflicts:
	src/Config/CS.props
Fix the Dynamo addin assembly path.
Merge remote-tracking branch 'origin/RevitSubFolders' into Revit2015

Conflicts:
	src/Config/CS.props
Update version path in addin.