Add tags functionality

- To each post's summary on homepage
- A page with all tags on them
- Each post has its tags listed

Based on https://github.com/danieldevries/jekyll-tag-generator
Fix tags in posts
Render RSS feed dynamically and with supported tags
Remove Atom in favor of RSS
Add note for posts without comments
Less self-closing tags
New post - Tom Bihn Buzz - Sling Bag
Move task files to new bin dir
Embrace manually running deployment script instead of as git hook
Cache-busting for CSS