Issue #174: Yahoo historical prices unavailable (blais/beancount)

[Hugo Ideler]

New issue 174: Yahoo historical prices unavailable
https://bitbucket.org/blais/beancount/issues/174/yahoo-historical-prices-unavailable

Hugo Ideler:

It seems that fetching historical Yahoo prices is no longer supported using ichart.yahoo.com.

Example:


```
#!sh

$ bean-price --no-cache -e "EUR:yahoo/MSFT" --date=2017-07-06
ERROR : Could not fetch for job: DatedPrice(base='MSFT', quote='EUR', date=datetime.date(2017, 7, 6), sources=[PriceSource(module=<module 'beancount.prices.sources.yahoo' from '/usr/lib/python3.6/site-packages/beancount/prices/sources/yahoo.py'>, symbol='MSFT', invert=False)])
```



Current prices still work:

```
#!sh

$ bean-price --no-cache -e "EUR:yahoo/MSFT"
2017-07-07 price MSFT 69.46 EUR
```

This seems confirmed at the Yahoo forums: https://forums.yahoo.net/t5/Yahoo-Finance-help/Is-Yahoo-Finance-API-broken/td-p/250503 .