Remove extra whitespace
TravelAdviceEdition embeds many Actions

This code is the beginnings of an audit trail for these editions.
Actions will be added on save.
Provide a helper method for adding actions

This will be used as the simpler way of adding user actions to
TravelAdviceEdition models.
Allow comments for TravelAdviceEdition actions
Wrap 'publish' to create relevant actions for the acting user

When a user hits publish we want to store this as an action in the history.
Use 'build' instead of 'create' to make saves implicit

Rather than cause a database save on each action addition, we should
instead let the applications define the save logic implicitly.
Remove embedded in for TravelAdviceEdition

We won't ever be accessing the edition through the action (it's mongo
so it's embedded within the edition anyway) so this isn't necessary as
something to be computed for the object.
Merge remote branch 'origin/travel-advice-audit-trail'