make it possible to have an unindexed array property by specifying items: {}
add page schema, two page collections (about and help), and a couple test about pages
add components for rendering page layout
improvements to page layouts

* make the layout an object with rows as a property
* render bootstrap column classes based on column count
* dispatch block rendering based on block type, with a fallback that uses the Panel component to show JSON
* richtext block view
add behave test for portal page rendering
use 'name' instead of 'slug'
allow overriding a block's class
Merge pull request #261 from ENCODE-DCC/1465-portal-page-basics

1465 portal page basics