Rename server.py into dpserver and use rc.py

Objective
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- unify excutable name into `dp*`
- use new command-line interface introduced in `dpmanip`

Summary
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- introduce another configure loader in which configure is loaded into argparser instance
- rename `server.py` into `dpserver`
- change CLI of `dpserver`

PR status
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- related to #125 
I don't know what you say :(
Should I write default `nargs` settings?
It is not documented in [argparser document](http://docs.python.jp/2/library/argparse.html#nargs).