Refactor UpdateReplace exception

Use six.text_type to format error message, so that we can avoid
possible failure in unittest when switching to oslo.i18n.

Change-Id: I6979a3298ff5c3dac734bd7ad5534853bab1a7d8
Merge "Refactor UpdateReplace exception"
Move size update to Cinder volume

In order to align AWS compatible Volume resource with current AWS
behavior [1], this patch moves volume size extension to the native Cinder
Volume resource.

[1] http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-ec2-ebs-volume.html

Change-Id: Ie1410d98175e1e42a95ca0fba72c48ca643a0dc7
Partial-Bug: #1340093