Do not use standalone Mustache partial for main content

This causes the current indentation level to be applied to all lines
within the partial, causing havoc in HTML when using the textarea
element and content with new lines. e.g.

<section>
    {{>content}}
</section>

When the "content" partial contains the following:

<textarea>Foo
Bar</textarea>

You will get the following rendered by Mustache:

<section>
    <textarea>Foo
    Bar</textarea>
</section>

Notice the whitespace added before the "Bar" line? Yeah, well this now
becomes part of the textarea content!

By changing the main content to not be "standalone", the Mustache spec
wont add anything.