(PUP-121) Fix dynamic environments test to accept ::absolute classnames

One of the dynamic environment tests is an attempt to include a class
that is not in the default manifests during a puppet apply.  This
produces an expected error about the missing class; however, PUP-121
changed the message slightly because for future parser, relative
classnames get transformed to be absolute and an attempt to 'include
testing_mod' ends up reporting that ::testing_mod could not be found.
This commit just updates the test to check for ::testing_mod not being
found when working with future parser.
(PUP-2399) Fix my fix to the fix
Merge pull request #2769 from kurtwall/pup-2399-fix-fix

(PUP-2399) Fix my fix to the fix
(maint) Remove warning about expect().to in specs

The Puppet Gemfile is pinned against RSpec 2.11.x, so there should be any
reason to worry about RSpec 2.9.x.
Merge pull request #2775 from Sharpie/remove-rspec-29-warning

(maint) Remove warning about expect().to in specs