Install RSpec 2.99 beta1 for builds.

The travis build failed because the spec:deps task
was installing RSpec 2.13, not RSpec 2.99.
Revert "Revert "Update to rspec 2.99""

This reverts commit 1d8debe29d2352c57d80afafd4fec066b1a6b8ef.
Merge pull request #2703 from myronmarston/rspec-299-upgrade

Rspec 2.99 upgrade