Add lifecycle support to buckets.

See: https://cloud.google.com/storage/docs/lifecycle and
     https://cloud.google.com/storage/docs/json_api/v1/buckets

Addresses 'lifecycle' part of 314.
Adding extra parameters for querying Cloud Storage keys.
Testing interaction with page token and extra params in iterator.

Also making sure tests pass by using the `upload_` prefix
instead of the `set_contents_` prefix.
Using {} as default in iterator for extra_params and get_query_params.
Updating docstring in Iterator.get_query_params.
Merge pull request #343 from tseaver/314-bucket_lifecycle_support

Add bucket lifecycle support
Merge pull request #332 from dhermes/add-params-to-key-iterator

Adding extra parameters for querying Cloud Storage keys.