Allow to filter stacks by owner names and project names instead of
ids only, in order to be consistent with other *_info modules.

Renamed stack_info's module attributes 'owner_id' to 'owner' and
'project_id' to 'project' to account for the new filter by name
functionality. Added the *_id attributes as aliases to keep
backward compatibility.

Updated and extended DOCUMENTATION, EXAMPLES and RETURN docstrings.

The stack_info module will convert its return values into dictionaries
without computed (redundant) values. Thus dropping values such as
location is not required anymore.

Change-Id: I9cdfb44dd424f63c05943616cf5918ceb3a57b1f