Whitelist DAOs 1/2

[sripwoud]

Similar to github org whitelist

Implement and deploy server API to:
For DAO voters group:

1. Query top 100 DAOs ranked by membership count
2. Query all voters of the DAO, write to a db along with timestamp of the most recent vote

[sripwoud]

Closed by #13 and #18

[sripwoud]

re opening
changing the API to be something like
GET /user/:username/belongs-to-voters-group