Trial Jinja 2 as templating system

[aron.carroll]

Percieved benefits of switching to Jinja 2

• Block inheritance for base templates which is much simpler to understand.
• Large number of developers (and designers) are familiar with it due to its similarities with the Django templates.
• Should be much faster at parsing and rendering templates.
• Has localisation support.
• Good documentation both on it's website and on sites like Stack Overflow.

We should convert a couple of existing templates to test the switchover and then get peoples feedback.

[aron.carroll]

Closing this as we've decided to go with Jinja.

There's some basic docs here:

​https://github.com/okfn/ckan/blob/feature-2375-demo-theme/doc/templating.rst

And a template overview:

​https://github.com/okfn/ckan/blob/feature-2375-demo-theme/doc/template-blocks.rst

Generally it's worth looking at the Groups pages to see how they're built.