0.15.0

Bug Fixes

• dns: fix dns plugin not properly binding the callback to the parent scope (#666)
• hapi: fix hapi plugin losing the scope when a payload is sent (#667)
• tedious: fix error for stored procedure calls in tedious requests (#662), fixes #661

Features

• core: add circular references handling when adding object tags (#659)
• couchbase: add couchbase plugin (#632)
• grpc: add grpc client and server plugin (#547), closes #311, thanks @nunofgs!