Fix info handler not returning numberOfPoints in Retentions, which was due to incomaptible type conversion between retention protocols.
Fix info handler not returning numberOfPoints in Retentions, which
was due to incomaptible type conversion between retention
protocols.

deniszh/go-carbon,lomik/go-carbon,deniszh/go-carbon,lomik/go-carbon,lomik/go-carbon,deniszh/go-carbon