Came to silence an uninitialized @body_parts but thought I'd tidy up a little while I was here.

Hi, I needed to silence a warning over an uninitialized @body_parts variable but then thought I'd do the whole "Boy Scout Rule" thing and do a little housekeeping. 

- Upgraded RSpec to 3.1.0 and converted syntax.
- Ran Rubocop on the codebase.
- Ran `bundle exec rspec --warnings` and silenced warnings in specs
- Check if the @body_parts are defined before checking if it's got a value.