Add rake to gemfile to fix travis build failures
Add rake to gemfile to fix travis build failures

felixonmars/planout,etosch/planout,mohnish/planout,rawls238/planout,kkashin/planout,felixonmars/planout,felixonmars/planout,mohnish/planout,mohnish/planout,cudbg/planout,etosch/planout,etosch/planout,rawls238/planout,etosch/planout,kkashin/planout,dieface/planout,cudbg/planout,cudbg/planout,cudbg/planout,marquisthunder/planout,rawls238/planout,dieface/planout,kkashin/planout,felixonmars/planout,mohnish/planout,rawls238/planout,dieface/planout,marquisthunder/planout,dieface/planout,marquisthunder/planout,kkashin/planout