Rename present to running, add new present state

The new present state just makes sure that a container exists, not that
it's running, although it get started one creation.
This is very useful for data volumes. This also changes the old
present, now running (default) state to only create the container if
it's not found, otherwise it just get started.

See also discussion on mailinglist:
https://groups.google.com/forum/#!topic/ansible-devel/jB84gdhPzLQ

This closes #6395
Merge pull request #6486 from discordianfish/docker-module-add-running

Rename present to running, add new present state