Refactored stack_info module and allow to filter by owner and project names

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