Remove neighbor frontmatter support
Move proxy/ignore/content_type Resource methods into the Resource class
no longer need warning
Fixup after rebase
Merge pull request #1313 from bhollis/remove_neighbor

Remove neighbor frontmatter support & move resource methods into Resource
Remove partials_dir functionality
Merge pull request #1318 from bhollis/partials_dir

Remove partials_dir functionality
Convert Sitemap::Extensions into actual Middleman::Extension
Experiment with Contracts
Merge pull request #1311 from middleman/contracts

Experiment with Contracts
Opt in paths, then allow ignores