You should already have a Socialcast community. For the group_id you'll need to
call the API to figure out the underlying integer group id for a group.

1. api_domain (e.g. foo-com.socialcast.com)
2. username (user to post message on behalf of)
3. password (password of user to post message on behalf of)
4. group_id (OPTIONAL Id of a Socialcast group to post the message into)

