changed to RSpec's expect syntax

I decided to change clearance to expect syntax for a project I was working on.  If, you want what I did, great!  If, not, you can just close this.

Please note, I have not done a poll request before.  If I have done it incorrectly, I apologize.
@derekprior I think I fixed all the lines you commented on.  I am not sure why it is saying there is a line that is too long in spec/clearance/session_spec.rb.  I do not see one that is too long.