update rails to 4.2.0
serve_static_assets deprecation warning
rspec 3 `expect().to` syntax
rspec 3 syntax changes

* `allow().to receive`
* more `expect().to`s that I missed
shorten that line up a little
remove deprecated rspec/autorun
rails config: use secret_key_base

instead of secret_token
rspec v3.1 adds support for rails 4.2

https://github.com/rspec/rspec-rails/issues/1187
Merge pull request #74 from alxndr/update-rails

rails 4.2.0, rspec 3.1