Wrong usage of "a"

Wrong usage of "a"

Wrong usage of "a" in the mesages:
"Convert list of dicts to a indexted dict"
"Attempt to create a initiatorGroup"
"Return a empty"
"Return a object containing the parsed output"
"where volume is either a dict or a oslo_versionedobject"
"this is a update from legacy driver"

Should be:
"Convert list of dicts to an indexted dict"
"Attempt to create an initiatorGroup"
"Return an empty"
"Return an object containing the parsed output"
"where volume is either a dict or an oslo_versionedobject"
"this is an update from legacy driver"

Totally 6 occasions in Cinder base code.

Change-Id: I209fa7817f531107ae15a980f81c02fe63dd557e