DKIM signing code cleanup.

Documenting the UTF-8 fix by @asiermartinez and the boto version bump…

…. Releasing as 1.5.

Remove some code that was breaking on boto 2.1. This is being release…

…d as seacucumber 1.3.

Adding support for rate limiting.

Here's 1.1. Not much different functionally, just a few fixes that bo…

…thered me.

Switching us to production/stable.