Remove Ruby 1.9.3 testing
Remove Ruby 1.9.3 testing

RVM doesn't have 1.9.3 anymore so we can't do this.

Signed-off-by: Tim Smith <764ef62106582a09ed09dfa0b6bff7c05fd7d1e4@chef.io>

chef/mixlib-install,chef/mixlib-install,chef/mixlib-install