Take advantage of date_to_rfc822

Jekyll has a filter built just for this purpose
Output Jekyll output if ENV['DEBUG'] exists
Add the paginator as a plugin: jekyll-paginate
Bump to jekyll-paginate 1.0.0
Merge pull request #2455 from jekyll/extract-pagination-generator
Update history to reflect merge of #2455 [ci skip]
Merge pull request #2437 from pathawks/date_to_rfc822
Update history to reflect merge of #2437 [ci skip]