Fix kinesis pagination issue

Add support for non_aggregate_keys in the pagination
configs.

Also went through the other kinesis paginated operations
and verified that DescribeStream is the only thing that
needs non_aggregate_keys.

Fixes #270.
Only add existing value if search is not None
Merge branch 'kinesis-pagination' into develop

* kinesis-pagination:
  Only add existing value if search is not None
  Fix kinesis pagination issue