Update instructions for deploying to Heroku

Heroku no longer uses a gem, so update verbiage appropriately.
Also: the default stack is now cedar, so the option is not needed.
Merge pull request #236 from brookr/master

Here's a quick change to the Heroku docs...
Fixed Incorrect github link
Implements infinite scrolling

- Implements infinite scrolling by binding to the scroll method
- Changes pagination from a clickable div to a nice looking spinner when loading messages
- Adds silence_mentions to make sure mentions are not fired when loading old messages
- When pulling old messages we do not navigate to oldest message anymore
- Fixes #186
- Fixes #180
Updated some gems that were updated to work with Rails 3.2.13
Fixes to deal with empty channels
Updated backbone.js to 1.0
Merge pull request #238 from gabceb/180

Implements infinite scrolling
Update .travis.yml
adding some bootstrap love to devise forms
Fixes #174. Prints a pithy message if you misuse /me
Merge pull request #244 from donthorp/kandan-174

Fixes #174. Prints a pithy message if you misuse /me
updating gems for 1.2 release
mini-revert
updated Changelog for 1.2
cleanup
Fixed Version Number in the /about page
Refine routes
Remove duplicated and unused routes
remove protocol of googleapis, Fixes #245
Fixes 232 Emojist only show once per line, fix indentation