Merge pull request #1 from jefferai/master

Don't use default parameters for booleans as they'll override default settings on the site.
Added missing Message params.
Merge pull request #2 from shazow/message-params

Added missing Message params.
Allow http Transport override.
Merge pull request #4 from shazow/appengine

Allow http Transport override (enables support for AppEngine)
fix up license comments, start add of mailchimp api