Check plugins using the Sensu API should support queries via Enterprise Dashboard API Federation

[cwjohnston]

Expected behavior

As a Sensu operator I want to configure checks which rely on the Sensu API to make API queries via the Enterprise Dashboard's API federation feature.

Current behavior

A number of check plugins in this collection, e.g. check-aggregate.rb, do not support querying aggregates via Enterprise Dashboard API federation.

Context

Without being able to make queries via API federation feature, checks which rely on API queries are tied to the availability of a particular API host.