Closes#6390
- check if more posts should be loaded whenever one is deleted
- delete dead code from posts controller
- delete duplicate component gh-infinite-scroll-box
- simplify posts-list-item `posts.post` or `editor.edit` link logic by modifying `gh-content-view-container` to yield necessary vars directly and use inline ifs in template
- add `gh-tag` component for rendering tags and updating infinite scroll box on `settings/tags` page
