Added the add_subscriber API call.
Flipped the correct call signature.
Allow already subscribed errors to pass silently when adding new subscribers.
Added tests and other helpers.
Merge branch 'master' of https://github.com/roverdotcom/django-fuelsdk into issue-3
Install the package.
Merge branch 'master' of https://github.com/roverdotcom/django-fuelsdk into issue-3
Updated readme docs.
Merge pull request #3 from roverdotcom/issue-3

Implement Add Subscriber call