Fix strip problem with scope

Scopes supplied with spacing around the `,` separator result in malformed scopes sent to Google, e.g. 

```ruby
scope: "userinfo.email, userinfo.profile, https://www.google.com/m8/feeds"
```

results in `invalid_scope` response from Google.

This simple fix strips any whitespace from around the supplied scopes.

RVM configuration also flipped to the latest 'standard' of using `.ruby-version`