Poll badgekit

This adds support for polling badgekit-api to detect new instances of "contributor" badges.  When found, the recipients of the badges will be added to the contributions table.

The contributor badges themselves are defined in the new contributorBadges table.  Each entry must be associated with a particular system and badge slug in badgekit API.  The entry also described the team, bucket, and description that will be logged in the contributions table when a new badge instance is detected.  
`pollBadgekitApi()` (lower case L)