Retry on Trello::Error / Around filter suggestion

[hakunin]

Hi, I've go to the point where I run into Trello::Error's for rate limits frequently and now I have to put every single call into some sort of retry block.

It would be nice if there was something that I could just plug into the gem itself (around filter is all I need).

If the gem had around filter for calls, it would be extremely easy to do both:

1. api call caching
2. user defined automatic retries