Major changes: code refatoring and optiminazion, and bug fixing.

easycloud/common/libcloud.py

easycloud/common/openstack.py

easycloud/common/utility.py

easycloud/core/compute.py

easycloud/modules/aws_awssdk/manager.py

easycloud/modules/aws_libcloud/manager.py

easycloud/modules/chameleon_libcloud/manager.py

easycloud/modules/chameleon_openstacksdk/manager.py

easycloud/modules/gcp_googleapi/manager.py

easycloud/modules/gcp_libcloud/manager.py

easycloud/modules/openstack_libcloud/manager.py

easycloud/modules/openstack_openstacksdk/manager.py