Merge branch 'release-2.23.0'
Removing obselete core directory.
Bump support to 2012-12-12 API version.
Add support for health checks
Add health_check param
Prevent implicit string decode in hmac-v4 handlers. Fix #2033
better error for unknown region - fixes #1983
Merge branch 'release-2.24.0'
Add nose Route53 tags to route53 tests to allow for simple testing of just Route53 APIs
Refactor base class to simplify setup of multiple testcases
Update (c) messages to match boto style
Update to the 2013-04-01 API and add support for string health checks
Factor attributes to class level
Add documentation
GS should ignore restore_headers as they are never set.

Override the handle_restore_headers() method in gs.key to
do nothing instead of using the base method.
Added some unit tests for cloudfront
Merge branch 'release-2.25.0'
Finished implementation of RDS's DescribeDBLogFiles
Added support for RDS log file downloading
Fix a little typo bug in the S3 tutorial.  Fixes #2087.
Fixed the DDBv2 `has_item` support.

Thanks to dorfsmay for the report!