Updated to allow CMOR support

1. Added a tag in the XML file (cpdn_metadata_translations.xml) which
allows for variables to be named.  Tag is <out_name=>.  This allows
CMOR support.

2. Created a new XML file (cpdn_metadata_translations.xml) which should
be used from now on.  This contains the out_names for CMOR, plus
updated standard names and units.