Authors and tags update

- Adds `post_mappings.json` file needed for filtering by author, tag
- Enables tag output from Sheer
- Adds links to author names and tags on single post template
Swap attribute order
Merge pull request #34 from Scotchester/gh-pages

Authors and tags update
Merge branch 'gh-pages' of github.com:cfpb/cfgov-refresh into gh-pages