Fixed copy-paste errors in ratelimit_remaining (#30)
Added missing -s as per @colinc's comment https://github.com/chriswarren/desk/issues/29#issuecomment-38822520
X-Rate-Limit-Reset now contains "seconds remaining until the next window begins", aka retry-after; not a timestamp
TooManyRequests (429) now handled by desk gem (#29)

Handling as EnhanceYourCalm, because TooManyRequests is already taken by another exception.
Merge pull request #31 from snowplow/feature/too-many-reqs-wait

EnhanceYourCalm fixes