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
Delegate :username rather than using a class method.

This is just a little cleaner?
fix for nil session in mobile_detection.rb
rename `date` to `unboundDate` because it is unbound.
FIX #1831: Dates were unbound on the profile page.
Merge pull request #1836 from nitper/patch-2

fix for nil session in mobile_detection.rb
Merge pull request #1826 from nporteschaikin/patch-1

Delegate :username rather than using a class method.
Update ember-cloaking to remove dependency on I18n
Non-staff users may not delete their posts in archived topics.
sub space for underscore in 'name' when registering public folder in plugin
Merge pull request #1837 from shivpkumar/master

sub space for underscore in 'name' when registering public folder in plu...
Update client.zh_CN.yml
Merge pull request #1838 from ofgeek/patch-1

Update client.zh_CN.yml
Update server.zh_TW.yml

modify chinese words/sentences to HK/TW style.
Merge pull request #1840 from worminfo/patch-2

Update server.zh_TW.yml
force_encoding according to the charset in mail, this solve encoding problem when not using ‘utf-8’ charset.
Merge pull request #1835 from HerbJiang/master

Fix reply by email encoding error when using non-ASCII & non-UTF8 charset
BUGFIX: remote upload dialog was broken
REFACTOR: Fixes poor class hierarchy for listing topics

- Upgrades Ember to latest
- Fixes a bunch of bugs with page titles and missing "active" states