Python plugin encoding

[roose]

Now, encoding is gb2312, but i use cp1251. Need detect system encoding or use https://pypi.python.org/pypi/chardet please

# ...
import chardet
# ...
rpc_request = json.loads(sys.argv[1],encoding=chardet.detect(sys.argv[1])["encoding"])
# ...

work for me on cyrillic and chinese, test please on you system

[qianlifeng]

I have tested chinese and english, it's ok, and I pushed those changes to v1.2.0