Add SDK Support for Amazon Elastic File System

Available under Aws::EFS::Client in the us-west-2 region, for preview
customers.

Amazon Elastic File System (Amazon EFS) is a file storage service for
Amazon Elastic Compute Cloud (Amazon EC2) instances. Amazon EFS is easy
to use and provides a simple interface that allows you to create and
configure file systems quickly and easily. With Amazon EFS, storage
capacity is elastic, growing and shrinking automatically as you add and
remove files, so your applications have the storage they need, when they
need it.

Author: awood45

CHANGELOG.md

@@ -1,6 +1,13 @@
 Unreleased Changes
 ------------------
 
+* Feature - Aws::EFS - Amazon Elastic File System (Amazon EFS) is a file storage
+  service for Amazon Elastic Compute Cloud (Amazon EC2) instances. Amazon EFS is
+  easy to use and provides a simple interface that allows you to create and
+  configure file systems quickly and easily. With Amazon EFS, storage capacity
+  is elastic, growing and shrinking automatically as you add and remove files,
+  so your applications have the storage they need, when they need it.
+
 2.0.45 (2015-05-21)
 ------------------