move book-reviews to correct path
create base layout with common structure and nest other layouts within it
helper to render Markdown string
merge excerpt/content into one file, delete extraneous extended files
move book reviews index page code to layout
create book review listing and display layouts
remove limit param from with_children_of call
reformat book reviews
Merge pull request #4 from dburrows/static-middleman

Book review WIP 

[closes #3]