Removing deprecation warning for Rspec

[afcapel]

Hi, the macthers are awesome and I have been using them for months without any problem, but recently updated to RSpec 2.6.0 and started to see a bunch of warnings like:

DEPRECATION WARNING: you are using a deprecated constant that will
be removed from a future version of RSpec.

* Rspec is deprecated.
* RSpec is the new top-level module in RSpec-2
***************************************************************

The following patch solved the problem for me, so hopefully it would be useful for others.

[sivabudh]

@cyx, do you have plans to merge this into the master?