Use Rails 4.1.8
Add bundler-audit

We've used this on a couple projects. Here's what it does:

* Scans your Gemfile for insecure dependencies.
* Uses publishd CVEs to find vulnerabilities.

To get set up with bundler-audit, this commit:

* Adds it to the development dependencies.
* Adds a rake task to invoke the CLI.
* Adds it to your default `rake` run.

https://trello.com/c/PltmBueK/210
v1.19.0
Add bundler:audit rake task description
Change JSON time format

The [Heroku API Design Guide][guide] says timestamps should be ISO8601.
By default, Rails uses millisecond-level precision.
This changes it to second-level precision.

[guide]: https://github.com/interagent/http-api-design#provide-standard-timestamps

* Before: `2014-10-20T20:31:29.542Z`
* After: `2014-10-20T20:31:29Z`
Use Ruby 2.1.5

https://www.ruby-lang.org/en/news/2014/11/13/ruby-2-1-5-is-released/
Use bin/setup from Travis

In order to test the executable documentation provided by bin/setup, we
should use `bin/setup` from CI.

I transitioned checks for gem presence to use `gem list --installed` and
to omit the `--no-document` flag. This flag should be decided by the
user's `.gemrc`.

Stop redirecting STDERR.

Expand grep flags and add --fixed-strings

The expanded flags tell me what this is doing. `--fixed-strings` gives a
tiny speed boost because we're not using regex here.
v.1.20.0
Add `bin/deploy` script

* Help avoid forgetting to run `rake db:migrate`.
* Help avoid forgetting to run `restart` after migrate.
* Allow each app to edit these deploy instructions to fit their
  environments' needs (such as `run rake purge` to clear a cache)
  but maintain the same `./bin/deploy` interface and convention
  that is consistent with our many Middleman and Rails apps.
* Use the shebang line for POSIX sh.
* Default the argument to 'staging'
Updated _flashes.html.erb with proper id

In Bitters' generated `flash.scss`,
the selectors use "-" instead of "_".

http://refills.bourbon.io/components/#flashes
Update header syntax in README template

* `##` syntax is easier when editing headers
* Also GitHub's recommended markdown style
* Reference: https://help.github.com/articles/markdown-basics/#headings
* Also changed project README