fix(legal): fix rendering of legal pages when loaded directly via url

I refactored the template fetching so that we can use it from the route handler when rendering pages dynamically and from the grunt task when generating pages statically.

Fixes #1372.

@shane-tomlinson r?
Can you add a note here about why `templateDest` instead of `templateSrc`? I think it's because we have already copied the templates to templateDest, but need to compile them?