Various cleanups to Ubuntu installation instructions:

* Avoid editing /etc/apt/sources.list add nginx repo, instead create
  /etc/apt/sources.list.d/nginx.list

* Avoid editing /etc/nginx/nginx.conf, instead put server_name_hash_buckets
  setting into discourse.conf

* Proper-case Discourse when it is referring to the product name, so that all
  the lowercase references are to the user created during the installation
Address @Supermathie's concerns in PR1430
Fix Post-rendering bug

Ember.Handlebars.normalizePath was being called with an object as
argument which caused it to error out.
also wrapped the return in a SafeString, so the html will not get
escaped again.
Adjustments to embedded content
Merge pull request #1823 from awesomerobot/master

fixing ol and ul preview/post incongruency
FEATURE: Show Reply count on blog index page when embedding
FIX: Don't store incoming links on embed
Support embedded link counts via `data-*` attribute
Let's put the "5 replies" back at the top of a comments section
FIX: suggested topics sometimes adds new topics from other categories before new topics of the current category
FIX: `currentPath` was not changing when transitioning to the same path.
Added a new hook to allow other kinds of analytics.
Merge pull request #1825 from awesomerobot/master

fixing the admin icon in the compose window
FEATURE: better top pages
BUGFIX: properly hide categories/top lists view when loading another tab
BUGFIX: cannot sort topic
Disallow auth callbacks in robots.txt
Delegate :username rather than using a class method.

This is just a little cleaner?
Page title includes page number for web crawlers
BUGFIX: groups page wasn't working
BUGFIX: could not save user's preferences when categories where watched/tracked/muted