sosreport module 2nd round PR

This is a superset of the commits that were in https://github.com/ansible/ansible/pull/5794. All comments from the previous ticket have been addressed except for checking if options are available by querying CMD --help as testing show that it was not needed on a CentOS 5 or CentOS 6 servers. The feature would be nice to share with other modules but more time and care should go into it.