* EMR:
   * --pool-wait-minutes option lets you wait up to X minutes before creating a
     job flow (#455)
   * Job flow ID included in error messages on failure (#452)
   * JOB and JOB_FLOW cleanup options (#485, #455)
 * EMR and Hadoop:
   * Compatibility fixes related to deprecated options and Hadoop's bizarre
     non-sequential version numbers (#489, #534)
 * Other:
   * Warn when *_PROTOCOL is not a class (#490)
 * Bug fixes:
   * Unicode strings can be used when specifying interpreters (#431)
   * --enable-emr-logging no longer causes the wrong counters/logs to be parsed
     (#446)
   * TMP_DIR inserted into 'sort' environment variables (#477)
   * Setting hadoop_home in mrjob.conf works again
   * Gzipped input files work when specified with relative paths (#494)
   * Passthrough options are not re-ordered when sent to Hadoop Streaming
     (#509)
   * json module is supported again if simplejson doesn't exist (#544)
   * HadoopJobRunner.path_exists() is no longer backwards (#549)