Fix transition smartdown flow lookup
Add a smartdown rake task, for renaming flows

As the flow directory name and coversheet name need to stay in sync
Rake tasks to convert smartdown flow state/name for trasition
Convert student-finance-forms Smartdown flow to transition

Renaming the flow to have '-transition' is the simplest way to let us run Smartdown
flows against regular flows without name clashes. This is a bulk rename as the app
and Smartdown kind of expect the flow name to match the directory/coversheet path.
Refactor Smartdown registry to treat transition like draft status

Transition flows, by convention, have a '-transition' suffix to distinguish them from
the original smart_answer version.

When in transition we always want them to be available on preview, so
treat them the same as draft status
Merge pull request #1106 from alphagov/transition-status

Make Smartdown flows with transition previewable
Add missing SPL outcome nodes

Use the outcome naming convention to derive potential snippets. Also
shows which things are applicable in this outcome
Add a TODO node, as a placeholder for missing step

This outcome can be used as a placeholder where the next question/outcome has not been
written, or is unknown. This allows next node rules to point at an outcome without
breaking the graph of the flow (which will be a linting error in the future)
Improve the SPL start page

Try to manage expectations a bit, for anyone working on the flow, or
testing it. Make clear it's not live yet
Support more question types in Smartdown visualisation