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.
```
digestable = "--#{salt}--#{password}--"
subject.encrypted_password = Digest::SHA1.hexdigest(digestable)
```