Update rspec syntax to use 'expect' and also change '==' to 'eq' and '=~' to 'match'

[durrantm]

Updated specs to use expect syntax.
As you may well know, using 'expect' over 'should' is a recommended practice because of dealing with delegate/proxy objects as detailed in http://myronmars.to/n/dev-blog/2012/06/rspecs-new-expectation-syntax.
As detailed in the blog post "In the future, we plan to change the defaults so that only expect is available unless you explicitly enable should. We may do this as soon as RSpec 3.0, but we want to give users plenty of time to get acquainted with it."
I noticed that expect is now being used in many of the major gems that use rspec.
I changed the pattern matchers from =~ to match() or match_array() as required for this change and while at it I also took the opportunity to change the == format to eq as recommended in the post.
All previously passing tests still pass after this change.
I have tried to observe the existing style. The only exception is some blank spaces on empty lines - but I kept the empty lines themselves.