Support rspec-rails < 4.0.0

[omarsotillo]

When trying to upgrade

  In snapshot (Gemfile.lock):
    rspec-support (= 3.8.2)

  In Gemfile:
    guard-rspec (~> 4.7) was resolved to 4.7.3, which depends on
      rspec (>= 2.99.0, < 4.0) was resolved to 3.8.0, which depends on
        rspec-mocks (~> 3.8.0) was resolved to 3.8.1, which depends on
          rspec-support (~> 3.8.0)

    rspec-rails (~> 4.0) was resolved to 4.0.1, which depends on
      rspec-support (~> 3.9)

[ethaning]

bump!