Was made so that the command line arguments can be omitted

In order to put the test framework, I have changed the directory structure

command line arguments can be omitted
- until now ./decanter.py -h hostname -p port -c config.module command
- from now ./decanter.py -c config.module command
  - hostname is localhost and port is 9000 if omitted

add --help
<pre>
./decanter.py --help
usage: --help [--help] [-h HOSTNAME] [-p PORT] -c CONFIG
              {start,stop,restart,status}

Example: ./decanter.py -h localhost -p 9000 -c config/devel.py start

positional arguments:
  {start,stop,restart,status}

optional arguments:
  --help                show this help message and exit
  -h HOSTNAME, --hostname HOSTNAME
  -p PORT, --port PORT
  -c CONFIG, --config CONFIG
                        config must match the location of a module containing
                        decanter required configuration items, i.e.
                        config/devel.py
</pre>