Altered ``get_bucket`` to use ``HEAD``.

This is mostly backward-compatible (& less expensive). However, if you were parsing exception messages from this method, you should refer to the documentation on how to change your code.
Updated the wording to stress that thousands of
keys weren't being fetched before.
Merge branch 's3-get-bucket-fix' into develop
Fixes #2082, #2078.
Fixed a test failure in Route53.
Added release notes for 2.25.0.
Bumped to 2.25.0!
Fixed a unit test failure in EMR.
Fix a little typo bug in the S3 tutorial.  Fixes #2087.
Fixed the DDBv2 `has_item` support.

Thanks to dorfsmay for the report!
Merge pull request #2088 from garnaat/fix-2087

Fix a little typo bug in the S3 tutorial.
Merge branch 'ddb2-fix-has-item' into develop
Fixes #2090.
Fix Param class convert method
Added ``boto.rds2``.
Added missed newline.
And fixed the copyright.
Removed ``example.com`` from Route53 tests.

This used to work but now produces ``InvalidDomainError`` responses.
Merge branch 'r53-remove-example-com' into develop
Fixes #2098.
Route53: expose EvaluateTargetHealth (mandatory for alias resource record sets)
Route53: add integration tests for alias rrs
Updated tests to remove the ``example.com``.