warns sysadmin to rebake all the posts

when changing the hostname
Fix rendering of email logs rows. Needed thead around the first row.
Performance: Improve Ember.Object.create speed
Merge pull request #1281 from ZogStriP/warns-sysadmin-to-rebake-all-the-posts

warns sysadmin to rebake all the posts
we need that <hr> in notification emails, I think
clarify on install
clarify on minimum reqs
slightly shorter copy for first post JIT education