Remove liveblog tag from AAA post
Add option for liveblogging

If the liquidvariable “livepost” is set to TRUE in a post YAML
frontmatter, instead of displaying the post date the header field will
display the current update time of the site.

After a livepost is completed, “livepost” should be set to false to
turn off this header banner.
Merge branch 'live-posts'