tests/platforms: add ruby21
tests/platforms: add ruby21

marcuskara/basebuilder,tsuru/basebuilder,actionjack/basebuilder,keymon/basebuilder,tsuru/basebuilder,keymon/basebuilder,marcuskara/basebuilder,keymon/basebuilder,jusbrasil/basebuilder,leandrosouza/basebuilder,ChangjunZhao/basebuilder,keymon/basebuilder,keymon/basebuilder,keymon/basebuilder,ChangjunZhao/basebuilder,axelerant/basebuilder,ChangjunZhao/basebuilder,actionjack/basebuilder,keymon/basebuilder,axelerant/basebuilder,jusbrasil/basebuilder,leandrosouza/basebuilder,keymon/basebuilder,jusbrasil/basebuilder,emerleite/basebuilder,leandrosouza/basebuilder,actionjack/basebuilder,emerleite/basebuilder,axelerant/basebuilder,emerleite/basebuilder,marcuskara/basebuilder