Usage template for all tools (uses --spark-runner LOCAL when used with a Spark tool)
    gatk AnyTool toolArgs

 Usage template for Spark tools (will NOT work on non-Spark tools)
    gatk SparkTool toolArgs  [ -- --spark-runner <LOCAL | SPARK | GCS> sparkArgs ]

 Getting help
    gatk --list       Print the list of available tools

    gatk Tool --help  Print help on a particular tool

 Configuration File Specification
     --gatk-config-file                PATH/TO/GATK/PROPERTIES/FILE

 gatk forwards commands to GATK and adds some sugar for submitting spark jobs

   --spark-runner <target>    controls how spark tools are run
     valid targets are:
     LOCAL:      run using the in-memory spark runner
     SPARK:      run using spark-submit on an existing cluster 
                 --spark-master must be specified
                 --spark-submit-command may be specified to control the Spark submit command
                 arguments to spark-submit may optionally be specified after -- 
     GCS:        run using Google cloud dataproc
                 commands after the -- will be passed to dataproc
                 --cluster <your-cluster> must be specified after the --
                 spark properties and some common spark-submit parameters will be translated 
                 to dataproc equivalents

   --dry-run      may be specified to output the generated command line without running it
   --java-options 'OPTION1[ OPTION2=Y ... ]'   optional - pass the given string of options to the 
                 java JVM at runtime.  
                 Java options MUST be passed inside a single string with space-separated values.