Added missing `bundle install` instructions.

I'm walking through the instructions and noticed that rake will not run unless a `bundle install` is performed so I added it to the instructions.
Change tiny date formatting for dates in past years. Example: 10 Dec '12
Logout takes you to the front page instead of leaving you on your user activity page
Admins who haven't been approved can log in when must_approve_users is enabled
Show the entire history of replies above a post when you expend "in reply to"
Update documentation

* Change recommendation for install path to /var/www/discourse
* Fix instructions for redis-server installation
* Set yourself as system user during install
* Clarify some instructions
Add GNU screen configuration file for vagrant love
Merge pull request #1306 from Supermathie/sysadmin-docs

Update documentation
Merge pull request #1307 from Supermathie/vagrant-screen

Add GNU screen configuration file for vagrant love
Added a missing "#" to href for TOS.
Merge pull request #1308 from happycollision/patch-1

Added a missing "#" to href for TOS.
Merge pull request #1303 from djensen47/patch-1

Added missing `bundle install` instructions.
Private message emails now include the history
create thumbnails by defaults

changed "create_thumbnails" default value to `true`
FIX: IE9 regression
Merge pull request #1310 from ZogStriP/patch-1

create thumbnails by defaults
Blocked Emails list in admin
Add a way to view staff action logs in admin
Add index to blocked_emails for last_match_at
Oops, forgot to use i18n in some places