Auto merge of #173 - olleolleolle:patch-2, r=bronzdoc
Auto merge of #173 - olleolleolle:patch-2, r=bronzdoc

Travis: use JRuby, 9.1.17.0 avoid double gem update --system

This PR updates the CI matrix Ruby versions, and avoids a step which `rvm` does now on its own.

bundler/gemstash,bundler/gemstash,bundler/gemstash,crashlytics/gemstash,crashlytics/gemstash,crashlytics/gemstash