WIP on porting to rspec 3

This is WIP and so will fail travis. This started as a whim but I've made good progress and there are now only slightly over 100 spec fails (on my osx laptop, I've only done a quick spot check on windows).

The remaining fails are all in 4 places:
* some uses of the `have_resource` matcher
* some uses of the `include` matcher
* some uses of the `pops/factory_rspec_helper.rb`
* one test in `spec/integration/util/feature_spec.rb`

I'm stepping away from this for a couple of days but wanted to put this up in case anyone wants to review the changes so far, or tackle some of the issues above.