Update Wiring Editor Copyright headers

Signed-off-by: Álvaro Arranz <aarranz@conwet.com>
Add a widget and an operator for test endpoint reordering

Signed-off-by: Álvaro Arranz <aarranz@conwet.com>
Add widget and operator endpoint reorder tests
Add tests for Wiring Editor Multiconnectors

Signed-off-by: Álvaro Arranz <aarranz@conwet.com>

Conflicts:
	src/wirecloud/platform/wiring/tests.py