Fix rake task in Travis CI by using bundler
Fix rake task in Travis CI by using bundler

DMPRoadmap/roadmap,CDLUC3/roadmap,CDLUC3/roadmap,CDLUC3/dmptool,CDLUC3/dmptool,DigitalCurationCentre/roadmap,CDLUC3/dmptool,CDLUC3/roadmap,CDLUC3/dmptool,DigitalCurationCentre/roadmap,CDLUC3/roadmap,DMPRoadmap/roadmap,DigitalCurationCentre/roadmap,DMPRoadmap/roadmap