[CloudFormation] Add waiter for stack completion
[CloudFormation] Add resources for stacks
[CloudFormation] Better populate resource attributes

Avoid n+1 redundant queries to populate stack resource attributes.

Per @trevorrowe’s comment: http://git.io/J2EFyw
[CloudFormation] Add Events resource
Merge branch 'master' into cloudformation_resources
[CloudFormation] Rename Event#event_id => Event#id
Fixed API documentation format.
Aws::RDS::Client now uses the 2014-09-01 API version.
Updated the API reference documentation for Aws::Kinesis::Client.
Added a :job_complete waiter to Aws::ElasticTranscoder::Client.

Also updated the API reference documentation.
Added support to Aws::CloudSearch::Client for configuring advanced Japanese language processing.
Bumped version to v2.0.3
Added next release section to the changelog.
Updated the list of supported service API versions.
PageableResponse no longer enumerates all pages in response to #count.

Fixes #106
Fixed api doc plugin for new waiter method source.
Updated Client documentation with better examples for configuration.
Internal name change for clarity.
Improved instance credential refresh logic.

When instance profile credentials are near expiration, it was possible
previously for multiple threads to trigger a refresh. While to code to
update the credential values was behind a mutex, it was possible for
multiple calls to be made.

Resolved this by verifying the credentials were not updated while
waiting to aquire the lock.

    def refresh_if_near_expiration
      if near_expiration?
        @mutex.synchronize do
          _refresh if near_expiration?
        end
      end
    end
[CloudFormation] Improve resources

Per @trevorrowe’s comment: http://git.io/rx3KYg