Review/Improve Introduction to Financial Python Tutorial

- This tutorial should use QuantConnect data.

In Pandas-Resampling and DataFrame, 
```python
monthly_return = aapl.resample('M').agg(lambda x: x[-1]/x[1] - 1)
```
should read
```python
monthly_return = aapl.resample('M').agg(lambda x: x[-1]/x[0] - 1)
```