Switch to new expect syntax.

I used some vim macros to do most of the work here:
http://nathanmlong.com/2012/11/convert-to-the-new-rspec-syntax-with-vim-macros/
Convert one more example I missed to `expect` syntax.

This one isn't run on 1.8.7 (the version I was using
last night when doing the conversion).
Merge pull request #208 from rspec/new_expect_syntax

Switch to new expect syntax.