Quick fix for first_available_file and role support

This is a fix on top of the 'airplane variable upgrade' commits that fixes legacy when_string so it evaluates correctly in the new eval construct.

Add support for shallow clones in the git module

make bin/ansible error output consistent for shell module as for the command module when no arguments are given

implement --start-at-task option to hop to a specific task before starti...

Adds a riak module

make bin/ansible error output consistent for shell module as for the command module when no arguments

Typo in docs

Fix Jinja2 filter plugins initialization

Add base64 encode and decode filters to templates

make json valid

Decided to not deprecate legacy template syntax for now.  Backwards compat is important, though the docs will suggest the new way.

Some continued work on new-style templates and associated test code changes.  Legacy template functions
are marked with "legacy_" for possible future removal.

allow references to names of variables in with_items without needing to surround them with Jinja2 '{{' delimeters

Technically this isn't quite valid YAML when this happens, so we make it valid.  This means that if a future commander
API allows save/load it should make sure it does similar processing.

Add code to flag legacy templating like $foo.{bar} as deprecated in favor of Jinja2 {{ foo.bar }} so we
can remove the legacy system at a later date.

Allow jinja2 evals that produce lists to be used in with_items.  Ideally want something a bit less heavy
than the eval here.

compensate.