Add error handling for date sorting, and normalize page type. Remove duplicate sort action from build_blog(). Ignore documents for which post-normalization has not indicated that a post should be ignored (via a new metadata value `ignore`).
Add error handling for date sorting, and normalize page type. Remove duplicate sort action from build_blog(). Ignore documents for which post-normalization has not indicated that a post should be ignored (via a new metadata value `ignore`).

chriskrycho/step-stool,chriskrycho/step-stool