Store historical prices from sources that provide CSV files.

[nochiel]

Maintaining a database of prices from specific exchanges is difficult or infeasible because exchanges are rate limited so downloading the entire history of bitcoin prices can be slow/unreliable.

If Spotbit is to have a database of prices, it should be as easy as possible to maintain the code and ensure the integrity of the data.

To that end:

• Teach Spotbit to import files from sources that provide csv files of all recorded price history:
  • [ ] Yahoo Finance
  • [ ] Coindesk
  • [ ] blockchain.info
  • [ ] Google's BigQuery
• [ ] Store these prices in sqlite for easy querying.
• [ ] Add an option that allows Spotbit to use it's saved data offline instead of querying exchanges.

[k9ert]

Good point. From a user`s point of view, i think this should be like a wizard with steps somehow like those:

• Choose the exchange you're interested in!
• Are you interested in historical prices (y/n)
• Ok, we're now downloading and importing the historical data for that exchange. After that we'll from now on store the current price every x minutes.

For applications which might query the data, it shouldn't make a difference where the data came from initially. Does that make sense?

[moneymanolis]

* Teach Spotbit to import files from sources that provide `csv` files of all recorded price history:
  
  * [ ]  Yahoo Finance
  * [ ]  Coindesk
  * [ ]  blockchain.info
  * [ ]  Google's BigQuery

@nochiel about which data frequency are we talking here? I'd say daily data is a non-issue but I am not so sure about intra-day data. Which data frequency are you aiming for?