CLC-3565, rspec to v2.99.0 to get deprecation warns prior to v3 upgrade

https://jira.ets.berkeley.edu/jira/browse/CLC-3565

RSpec 2.99 was developed in tandem with RSpec 3. "Every breaking change in 3.0 has a corresponding
deprecation to 2.99" per https://relishapp.com/rspec/docs/upgrade. I will tackle some of the deprecations in a subsequent PR (e.g., account for rspec-core 3 removal of `its` method by adding rspec-its gem)