4239: Update Python SDK for google-api-python-client 1.3.

This package renames the module from apiclient to googleapiclient.  It
provides a shim apiclient module for compatibility, but it only
exports the appropriate names, not real submodules.  Using it requires
changing imports like

    import apiclient.errors

to

    from apiclient import errors

This approach works (has been tested) with both versions 1.2 and 1.3.
Closes #4239.
added by_id subdirectory notes and arvados#collection

No issue #.