Add CMX support to pig.tmpfilecompression.codec

Pig has supported compression(GZ, GZIP, LZO). But latest pig has not supported CMX codec yet. cmx is "com.ibm.biginsights.compress.CmxCodec". This information also could be found from latest release pig-0.13.0 documentation: http://pig.apache.org/docs/r0.13.0/perf.html.
Besides, I once tested CMX codec with pig-0.13.0 before. Following was the current settings:
SET pig.tmpfilecompression true;
SET pig.tmpfilecompression.codec cmx;
Error:
Caused by: java.io.IOException: Invalid temporary file compression codec [cmx]. Expected compression codecs for org.apache.pig.impl.io.TFileStorage are GZ,GZIP,LZO.