AWS credentials delegation to S3/Swift3

[Attila Fazekas]

Now (openstack-nova-api-2012.2-1.fc18) , when the nova tries to connect to the S3 storage it tries to use the credentials "hard coded" to the config file.
It means every RegisterImage call will use the same tenant credentials instead of their own tenant credentials.

I think nova should delegate authentication to the swift backed, even by using other access method with the original requester permissions/roles.

Note1:
Probably this behaviour originated the days where the nova-objectstore used and it does not validated credentials.
Note2: Part of AWS credential is a signature of the request by the secret key, simple forwarding probably will not work.