Fixed DynamoDB batchGet for situations where the batch request size
exceeds the DynamoDB limit. Not, batchGet returns a Stream of Item.
Removed flatten calls.
Fixed SimpleDB.domains.
Fixed SimpleDB.select.
Added tags method.
Added support for instanceStatuses.
Added support for reserved instance offerings.
Added generic sequencer.
Added support for filters on instanceStatuses.  Added support for
availability zones on reservedInstanceOfferings.
Added support for filters on tags.
Use new Sequencer trait.
Added support for filtering steps by clusterId and stepStates.
Added support for clusterId filtering on bootstrapActions.
Added clusters.
Fixed issue with created clusters request.
Use Sequencer trait.
Use Sequencer Trait.
Eliminated general imports.
Added comments describing Sequencer.
Eliminated redundant import.