Add a Nuance GitHub repository source and basic polling
Summary: Ref T10537. Ref T10538. This calls GitHub, sorta?
Test Plan:
$ ./bin/nuance import --source poem <cursor:events.repository> Polling GitHub Repository API endpoint "/repos/epriestley/poems/events". <cursor:events.repository> This key has 4,988 remaining API request(s), limit resets in 1,871 second(s). <cursor:events.repository> ETag for this request was ""4abdd3d66ad5ca38f5117b094e76f4ba"". array(4) { [0]=> array(7) { ["id"]=> string(10) "3733510485" ...
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T10537, T10538
Differential Revision: https://secure.phabricator.com/D15439