Add structure to templates folder

[mikeckennedy]

I would like to move layout.py / layout.jinja2 to a folder called shared and rename them to _layout.* to indicate they are never meant to be the top-level template. Thoughts?

[stevepiercy]

I understand why this is important, but this is a highly subjective matter. Some developers toss all templates into templates, some use a shared or core, some organize templates to align across models and views, and still others organize into self-contained Python modules.

[mikeckennedy]

Sure, fair enough. :)