CLN: Make io/data urls easier to monkey-patch
This could be useful to make pandas more resilient to basic url changes
like that which happened with yahoo finance.  That said, clearly
wholesale API changes won't be helped by this.

What do you all think, worth it to make this relatively trivial change?

What about factoring out the function that generates the URL it self so that could be monkey patched. That way pandas can be resistant to more than just changes to the base URL.
 Certainly something to consider, but most of the functions are basically
just params --> transform --> pass url to common function anyway.
 This looks like a good incremental change to me. merging. Don't think something more 
elaborate is called for.
