Enable getting deep list outputs from the port models.

Can now pass a set of indices to RunPort#value and get list outputs.
Add a method to get a route (path) to a port.

Can now ask a port for the route to its values.
[TAV-465] Refactor renderers and add list rendering.

Renderers now operate on outputs not just data. Rendering list outputs is moved
fully into the renderers and out of the helpers.
Factor out common list handling code for sharing.
Rename and re-document renderers.

No longer just for outputs, so renamed to reflect that.
Merge branch 'rh/new-outputs'

* rh/new-outputs:
  Rename and re-document renderers.
  Factor out common list handling code for sharing.
  [TAV-465] Refactor renderers and add list rendering.
  Add a method to get a route (path) to a port.
  Enable getting deep list outputs from the port models.
Rename taverna_server initializer and document.

Needs to be called taverna_server.rb.example initially so it doesn't get pulled
in when rails boots.

Documentation also updated.
Update documentation for overriding models.

More can now be overridden.
Bump version number and update change-log.