Generate precompiled layouts and email layouts (for attendease internally) separately from plugin generated pages.

- Use an `EventLayoutPage` generator so a precompiled layout is generated on first compile (if the theme doesn’t already have a `attendease_layout` defined)
- Generate the `attendease_layout/emails/layout.html` file if it isn’t already defined in the theme.
- Point page generators to the layouts in `_attendease_layout`
Subclass name simplification.
Increment the version. Oh Six Two!
When generating a precompiled layout use “Hello” as the base title.

Use the base_layout passed in to determine which layout to render for email and html.
Update specs to point to the `_attendease_layouts` folder for page generation layouts.
Don’t pollute the source code.

Keep all files used for page generation under _attendease
Write an extremely simple base layout if they are missing.
Update specs for pre-compiled and page generation layouts.
Note about base_layout and base_email_layout
Use the template and base_layout to generate the layout files for page generation.
Ensure the {{ content }} tag is available on pre-compiled pages.
Merge pull request #41 from eddanger/precompiled-and-page-layouts

Generate precompiled, page and email layouts independently.