This way we guarantee there will be at least one translation for a model
and we keep compatibility with the rest of the application, which
ideally isn't aware of globalize.
Updating it required reorganizing the form so translatable fields are
together.
We also needed to add a `hint` option to the form label and input
methods so the hint wouldn't show up for every language.
Finally, the markdown editor needed to use the same globalize attributes
as inputs, labels and hints, which adds a bit of duplication.
There's no reason to only convert Markdown to HTML in translations when
their body changes but to always convert it when the "main" body field
changes.
Whether we should always use the condition or never use it is something
we can debate about, though.
