optimize the command help, and add build version in VERSION

Changes:
1) Add a method getHeaderDescription() in Command interface. When displaying command help, will also display the header. It can be description of this command, and can be a example command line.
2) Change 
        public void process(CommandLine cl,
                @SuppressWarnings("rawtypes") Map stormConf) throws Exception;

to public void process(CommandLine cl) throws Exception;
Each command should be free to decide how to parse the command line, instead of we parsing it for the user.

I will add more storm commands into this command list, and it depends on this. These command includes storm topoogy kill, rebalance, and list.

3) Change a version string to a Version class. We add a BUILD number in the Version, so it is more easy for us the track the changes in a mixed deployment environment.