Add user feedback when a user hits their account rate limit

[CloudNiner]

We currently don't provide any feedback in the UI when a user clicks around fast enough to hit their Climate API rate limit. The chart spinner just spins indefinitely.

We should provide a helpful message that tells the user when they should try again, or even better, provide a message such as "retrying automatically in seconds" and automatically refresh when the rate limit period expires.

[rmartz]

Similar to #130, having a user message may be a much superior way of handling the problem than just invisibly re-trying failed requests in the background.