Add Jinja2 as the project templating language
Move inject variables into layout
Add a include_raw Jinja extension

This allows us to include raw files directly into templates without
them going through the Jinja processor.
First pass at converting templates to Jinja

Most content is now correctly using Jinja but the rendering in the
sidebar is not working correctly.
Don't insert the ng-csp attribute if unset

Angular will not load correctly if this attribute is present but empty.
Move all angular templates into a client directory
Update the auth template to use Jinja
Remove the home template as it's no longer used
Update the bookmarklet to a Jinja template
Convert pattern library to use Jinja
Convert the email templates to use Jinja
Ensure embed.js is rendered correctly

Now using js rather than txt as the file extension as it provides
a clearer indication as to the contents of the file. The fact it's in
the templates folder should be enough to indicate it needs processing.
Move includes into their own directory
Move base.html into a layouts directory
Remove blocks.html as it's now unused
Update the notification template to use Jinja
Convert text email templates to use Jinja
Add Jinja config to production.ini
Add Jinja to the list of dependencies
Update the notification tests to work with Jinja