Cleanups for change I35c3b266b3c733f6b1629de4c683ea7d40128032
Add missing param definitions to client get_container
and head_object docstrings.
For consistency, add headers parameter to the Connection class
head_object and head_container wrapper methods.
Add tests to verify that the headers parameter of Connection
get_container, head_container and head_object methods is passed to the
module functions.
Change-Id: Ib40d5b626b2793840727c58cffbf725bea55651f
328d6a8d45