Address ruby warnings:

./lib/rspec/core/example.rb:225: warning: method redefined; discarding old inspect
./lib/rspec/core/example.rb:210: warning: previous definition of inspect was here
Leverage rspec-support’s shell out methods.
Address ruby 1.9.3 warnings.

warning: assigned but unused variable - _ignored
ruby/1.9.1/gems/minitest-5.4.0/lib/minitest.rb:46: warning: (...) interpreted as grouped expression
Make the spec pending on 1.9.2 since I can’t repro the travis failure.

  1) RSpec behaves like a library that issues no warnings when loaded issues no warnings when loaded
     Failure/Error: expect(stderr).to eq("")

       expected: ""
            got: "<internal:lib/rubygems/custom_require>:29: stack level too deep (SystemStackError)\n"

       (compared using ==)

       Diff:
       @@ -1 +1,2 @@
       +<internal:lib/rubygems/custom_require>:29: stack level too deep (SystemStackError)