S&P 500 data daliy download

Package: pycrawlers.example.sp500

-   Name: get_SP500_daliy_quotes
-   Input:
    -   date: A string of date, of format "yyyy/mm/dd".
-   Output: A list of 500 companies data frame

http://nbviewer.ipython.org/github/wen777/PyCrawlers/blob/master/dev_ipynbs/_hsiangdev/Dev__hsiang20141128_dailyNovStockQuotes_packaging.ipynb