Update of finance.py to (O,H,L,C) instead of (O,C,H,L)

In the financial world, a bar-chart is commonly called an OHLC-chart or "Open-High-Low-Close chart". Also see http://en.wikipedia.org/wiki/Open-high-low-close_chart or simply google around.

To my surprise this library uses a sequence of OCHL instead of OHLC. Although it changes the API, I found it important to comply with financial industry standards. This makes it easier to implement this library in existing financial software and thus more likely for the library to be used in the future.