sql2csv: Support encoding flag for query files (--query-encoding)

Created by: jonashaag

$ sql2csv ...
...
Your file is not "utf-8" encoded. Please specify the correct encoding with the -e flag.
Use the -v flag to see the complete error.

$ sql2csv ... -e 'iso-8859-1'
usage: sql2csv [-h] [-v] [-l] [--db CONNECTION_STRING] [--query QUERY] [-H]
               [FILE]
sql2csv: error: argument FILE: can't open 'iso-8859-1': [Errno 2] No such file or directory: 'iso-8859-1'