[LIBCLOUD-536] Add support for the Outscale SAS cloud.

This commit introduce the Outscale SAS cloud an european cloud provider
featuring an EC2 compatible API.

Special care have been taken to leave room for Outscale INC an US based cloud
using the same infrastructure but governed by US laws.

Signed-off-by: Benoît Canet <benoit@irqsave.net>