[WIP] i18n

Worked on this with @alicoding. The webmaker i18n module works pretty seamlessly with nunjucks. Some notes,

1. Client side templates are rendered through `middleware.staticTemplateViews` so it looks like if we localize those templates, the client templates will be localized. The only downside is we'll have to include template language in the actual localized string. It seems awkward at first, but it will give the localizers the ability to place the context where it should go. For instance, a string like `"Welcome to the backpack {{ user.name}}"` might be better localized as `"something something {{ user.name }} something something"`. So by distributing the full string, including the pieces that need to be template rendered.

(more soon)