Ruby and Rspec versions

Maybe .ruby-version shouldn't be in the repo, but since it is, this is the version available on Heroku Cedar (they don't offer REE). Might be good to test with both.

Also bumped Rspec.

This looks like a useful transitional gem. Unfortunately the specs are failing for me:

```
load_missing_constant': uninitialized constant Rspec::Rails23::Controllers (NameError)`
from /Users/nathany/Development/Fava/rspec-rails23/spec/lib/rspec/rails23/configuration_spec.rb:20
```