Rubinius is set as optional
Rubinius is set as optional

- build bug in travis-ci https://github.com/travis-ci/travis-ci/issues/2821

jrep/apiary-client,beni55/apiary-client,cvcnetwork/apiary-client,apiaryio/apiary-client,jrep/apiary-client,apiaryio/apiary-client,bireshwarWEBQ/apiary,beni55/apiary-client,cvcnetwork/apiary-client,bireshwarWEBQ/apiary,apiaryio/apiary-client