updated NEWS and UPGRADING with details of #1903

[closes #1966]

NEWS

-4.3.0:
+master:
+
+* Improvement: Paperclip now supports aws-sdk v2 (@betesh, @davetchen, https://github.com/thoughtbot/paperclip/pull/1903)
+    If your Gemfile contains aws-sdk (>= 2.0.0) and aws-sdk-v1, paperclip will use aws-sdk v2.
+    With aws-sdk v2, S3 storage requires you to set the s3_region.  s3_region may be nested in s3_credentials, and (if not nested in s3_credentials) it may be a Proc.
+
+4.3.0 (6/18/2015):
 
 * Improvement: Update aws-sdk and cucumber gem versions.
 * Improvement: Add `length` alias for `size` method in AbstractAdapter.
@@ -11,7 +17,7 @@
 * Ruby Versioning: Drop support for 1.9.3 (EOL'ed)
 * Rails Versioning: Drop support for 4.0.0 (EOL'ed)
 
-4.2.4:
+4.2.4 (6/5/2015):
 
 * Rollback backwards incompatible change, allowing paperclip to run on
   Ruby >= 1.9.2.

UPGRADING

 ##################################################
-#  NOTE FOR UPGRADING FROM PRE-3.0 VERSION       #
+#  NOTE FOR UPGRADING FROM 4.3.0 OR EARLIER       #
 ##################################################
 
-Paperclip 3.0 introduces a non-backward compatible change in your attachment
-path. This will help to prevent attachment name clashes when you have
-multiple attachments with the same name. If you didn't alter your
-attachment's path and are using Paperclip's default, you'll have to add
-`:path` and `:url` to your `has_attached_file` definition. For example:
+Paperclip is now compatible with aws-sdk >= 2.0.0.
 
-    has_attached_file :avatar,
-      :path => ":rails_root/public/system/:attachment/:id/:style/:filename",
-      :url => "/system/:attachment/:id/:style/:filename"
+If you are using S3 storage, aws-sdk >= 2.0.0 requires you to set the s3_region.
 
+If you want to continue using an earlier version of aws-sdk, replace
+ aws-sdk with aws-sdk-v1 in your Gemfile.
+
+If both are in your Gemfile, paperclip will use aws-sdk v2.