playbook structure checking.

Also be smart and don't run a play at all if no tasks in the play match any of the tags specified.  This includes not running the setup actions!

TODO: logrotate script and append to log instead.

Playbook will install ansible, create directory where git checkout goes,
and set up a cron job to run ansible-pull.

Revert "Revert "Actually wait for password prompt in remote sudo execution.  Totally breaks stderr debugging"

This reverts commit e1611403.

Conflicts:

	lib/ansible/connection.py

Demonstrate what happens when there is no default context in the policy.

Sudo support operational in both playbooks and main program.   Implementation could use some cleanup.

Remove the group membership example.  There's not much to twiddle with
the group module.  Give examples for what is possible.

This changes the gid option to group.  One may provide a primary group
as either a gid or a name.  The module will then check to verify that
the group already exists.  If the group does not already exist, the
module will fail.

Allow groups to be passed to runner API to make parse_hosts optional, misc fixes as a result of refactoring in Runner.
Cleanup in Playbooks module is next.

Allow variable expressions to be stored as variables themselves, do some things to allow setup strings
to more easily contain spaces without being mangled, which is neccessary because of the above.

Remove test from bottom of example that doesn't really make sense in the context of the example's use case.

refactoring of playbooks now warranted, which we'll do before we move on.   This variable assignment
system makes nearly all possible magic possible, for we can use these variables however we like,
even as module names!