Upgrade to rspec3 without mock/stub upgrade.
Update all old-style stubbing and mocking.

This mostly replaces stub with allow, but there are some other
deprecated things like stub_chain, unstub, and any_instance that also
had to go.
Appease The Hound.
Merge pull request #256 from CenturyLinkLabs/chore/upgrade-rspec

Upgrade to rspec3