Format the stock intraday trading data gotten from Google finance to be like below.
The usage:
	- specify input text file name and output csv file name in stock2csv.py
	- run 'python stock2csv.py'
********output********
DATE,CLOSE,HIGH,LOW,OPEN,VOLUME
2013-03-27 06:30:00,456.7,456.8,456.41,456.46,106553
2013-03-27 06:31:00,454.312,456.77,453.45,456.43,384917
2013-03-27 06:32:00,455.25,455.34,454.04,454.31,152004
2013-03-27 06:33:00,455.145,455.88,454.88,455.23,101717
…