update fog gem to latest
removed old rake task until it's updated
enable thumbnailing on S3

- added url to optimized image model
- refactored s3_store & local_store
Update INSTALL-ubuntu.md

The removed paragraph was useful for a previous version of the "Updating Discourse" code above it. It seems useless now, as precise instructions are already in the code comments. In fact, it became incoherent, as we explicitily have "bluepill quit" in the code now.
Merge pull request #1276 from jbruni/patch-1

Update INSTALL-ubuntu.md
Merge pull request #1275 from ZogStriP/enable-thumbnailing-on-s3

Enable thumbnailing on s3
Change category by editing first post updates topic title
Rename the PK index to support table rename
Upgrade jQuery to 2.0.3
FIX: Post Menu wasn't updating the bookmark icon properly.
cs translation update
add foreground color to @mentions
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