Adding new app for translation work. First pass at middleware to swap the site based on the user's locale.
Override the default menu in the admin to only show the language switcher.
Refactoring middleware and adding utilites for fetching/creating the language site.
Tests and fixes for get_site_for_language.
Tests for creating a new site.
Tests for middleware.
Thin wrapper command to create sites for languages.
Starting work on copying CMS content when creating a new site.
Copy the fields over for a form as well.
Touch up some comments.
Adjust management commant to copy the CMS content when creating a new site. Allow this to be disabled.
Page is the base for all content and shouldn't be copied on it's own since it will be created by the parent links when the actual content (RichTextPage, Form) is created.
New test to ensure that nested pages are copied correctly.
Bulk create isn't really a possibility so simplify the copy code to prevent divergent paths.
Ensure that nested forms and links are copied correctly.
Merge pull request #143 from mozilla/language-as-site

Language as a Site Groundwork
New admin mixin for adding translation helpers to the change form.
Simulate the admin popup to show the original english version of the content.
Add links next to translatable fields.
Plug the TranslatableMixin into the page/form admin classes.