Make s3 key buffer size configurable.
Merge branch 'release-2.9.4' into develop

* release-2.9.4:
  Bumping version to 2.9.4
Merge pull request #1506 from jterrace/configurable-bufsize

Make s3 key buffer size configurable.
Merge remote-tracking branch 'official/develop' into develop
Add sphinx extension for linking to github
Update release notes to use the new sphinx roles
Fix a bug always connecting to the default end point in dynamodb2's DynamoDBConnecting
Added tests for the dynamodb2 region fix.
Fix unit test

Must pass in credentials for unit tests.
Modifiy EbsOptimized param type in LauchConfig.

Since a couple of days ago, API expects a xsd1.1 boolean type for paramenter
EbsOptimized when LaunchConfiguration is created. This commit change old
True and False native python types for new lowercase string ones.
Added tests for the EBS Optimized change.
Merge branch 'ebs-launch-config' into develop
Added a failing test for no results to DDBv2.
Solving bugs on empty results and between comparisions

When it returns empty result the result _results_left is true by
default and it tries to get data that doesn't exist.
When a between condition is added on the query the parameters needs to
be two separated string values ( not a SS field )
Updated tests to accommodate the changes to ``_build_filters``.
Merge branch 'ddb2-improvements' into develop
Added support for web identity federation.
Merge branch 'github-links' into develop

* github-links:
  Update release notes to use the new sphinx roles
  Add sphinx extension for linking to github
Merge branch 'wif' into develop
Fixed headers in EC2 autodocs.