AI 147054: am: CL 147053 Add -hdf primer vars for the platform and release ID...

AI 147054: am: CL 147053 Add -hdf primer vars for the platform and release ID associated with the current (most recent) SDK.
  Currently, the docs that are specific to each SDK release -- downloading, installing, upgrading, requirements -- are stored in a directory with release-derived name, such as "1.1_r1". This change lets documents use generic links to point into the most recent version specific docs, eg href="{@docRoot}sdk/{sdkCurrent}/installing.html" instead of href="{@docRoot}sdk/1.1_r1/installing.html".
  Original author: ddougherty
  Merged from: //branches/cupcake/...

Automated import of CL 147054