storage: multi-thread add_measure in Carbonara based drivers
storage: multi-thread add_measure in Carbonara based drivers

We now get/update/put carbonara files in threads so we can process them
in parallel. This should improve performances a lot.

Change-Id: I74517dd5a7abdd071a6fa1bdf4e804291cbdce6a

sileht/gnocchi,sileht/gnocchi,leandroreox/gnocchi,idegtiarov/gnocchi-rep,leandroreox/gnocchi,idegtiarov/gnocchi-rep,idegtiarov/gnocchi-rep,gnocchixyz/gnocchi,gnocchixyz/gnocchi