Reformatted 'demo.things' model from distribution

Signed-off-by: Alex Tugarev <telekom@tugarev.de>
Implemented test for GenericItemChannelLinkProvider

Signed-off-by: Alex Tugarev <telekom@tugarev.de>
Moved files

Signed-off-by: Alex Tugarev <telekom@tugarev.de>
Renamed EPackage of Thing DSL

Signed-off-by: Alex Tugarev <telekom@tugarev.de>