Updating HDFS to use CHPL_AUXIO_INCLUDE and CHPL_AUXIO_LIBS

Changing HDFS to use CHPL_AUXIO_INCLUDE and CHPL_AUXIO_LIBS for library and include paths. Updating README.hdfs to reflect this as well.
This line and the comments in the section below should be re-flowed to match the rest of the file.