Set Sass-Rails Version

* I've gotten the error `undefined method 'environment' for
  nil:NilClass` on projects I've recently started with Suspenders.
* Upgrading the sass-rails version solves this issue.
Be less restrictive about sass-rails version

Per @derekprior's comment, we just need a minimum:

https://github.com/thoughtbot/suspenders/pull/303#discussion_r10825370
Bump to 1.9.1
fix small typo in unicorn.rb
Make it easy for developers to join Heroku apps
Enable SMTP/TLS in SMTP settings

Be more secure by default.

https://en.wikipedia.org/wiki/STARTTLS