ENYO-2263: revisit the given inspector "design" object to the indexer.

We want to keep the same entry name found in .design file (palette, inspector):
. object "propertyMetaData" is renamed "inspector" in the constructor,
. fix addDesign function; looking for propertyMetaData instead of inspector

Enyo-DCO-1.1-Signed-off-by: Marie-Antoinette de Bonis-Hamelin (Marian)
marie-antoinette.de-bonis-hamelin@hp.com