BUG: Make 'get_quote_yahoo' fail fast like other data functions.

Previously was catching `URLError` when other functions
let that bubble up. Should match other behavior in module.
CLN: Use DataError in io/data.

Bad form to use bare Exception, so created a new Exception
(`DataError`) that inherits from `PandasError`.

Doesn't affect existing code (because catching `Exception` will
still catch this error).