fix encoding issue for chinese(Non-English) Column passed from commandli...

if u  pass the chinese column to csvcut -c <HERE>（It also affect csvgrep, csvsort, csvjoin,...）, It will cause the proble as followed，because It can't process input encoding from command，

$ in2csv userinfos20140819.xls 
id,<中文1>,<中文2>
1,1212,88
1,1111,89
$ in2csv userinfos20140819.xls csvcut -c <中文1>,<中文2>
.....
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 19: ordinal not in range(128)
Original exception was:
.....
    raise ColumnIdentifierError('Column identifier "%s" is neither an integer, nor a existing column\'s name.' % c)