Metadata.hpp needs a <memory> include
Metadata.hpp needs a <memory> include

I'm not sure why this wasn't picked up by Travis, but build failed on
red hat due to missing <memory> include.

mpgerlek/PDAL-old,jwomeara/PDAL,jwomeara/PDAL,jwomeara/PDAL,Sciumo/PDAL,DougFirErickson/PDAL,DougFirErickson/PDAL,boundlessgeo/PDAL,lucadelu/PDAL,DougFirErickson/PDAL,lucadelu/PDAL,Sciumo/PDAL,mtCarto/PDAL,boundlessgeo/PDAL,mpgerlek/PDAL-old,DougFirErickson/PDAL,mtCarto/PDAL,lucadelu/PDAL,Sciumo/PDAL,mtCarto/PDAL,Sciumo/PDAL,mpgerlek/PDAL-old,radiantbluetechnologies/PDAL,boundlessgeo/PDAL,radiantbluetechnologies/PDAL,boundlessgeo/PDAL,radiantbluetechnologies/PDAL,radiantbluetechnologies/PDAL,lucadelu/PDAL,mtCarto/PDAL,mpgerlek/PDAL-old,jwomeara/PDAL