test(rspec): prevent minitest runner call on Ruby < 2.2
test(rspec): prevent minitest runner call on Ruby < 2.2

We had issues with running `rspec` on Ruby < 2.2.

This patch prevents Test::Unit's AutoRunner from executing during RSpec's rake task.

hauledev/has_account,hauledev/has_account,huerlisi/has_accounts,huerlisi/has_accounts,hauledev/has_account,huerlisi/has_accounts