sync API models and regenerate modeles (#357)

Updates the SDK's API models, and generated clients to the latest release versions.

Author: jasdel

CHANGELOG_PENDING.md

@@ -1,3 +1,7 @@
+### Services
+* Synced the V2 SDK with latest AWS service API definitions.
+  * Fixes [#359](https://github.com/aws/aws-sdk-go-v2/issues/359)
+
 ### SDK Features
 
 ### SDK Enhancements
@@ -14,5 +18,3 @@
   * Fixes the iamSecurityCredsPath var to include a trailing slash preventing redirects when making requests to the EC2 Instance Metadata service.
   * Fixes [#351](https://github.com/aws/aws-sdk-go-v2/issues/351)
 
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