Use rvm 2.1 instead of 2.1.0 at .travis.yml
Use rvm 2.1 instead of 2.1.0 at .travis.yml

This is a workaround for the rvm bug.
See https://github.com/travis-ci/travis-ci/issues/2220

Pluto1010/packer-templates-1,d-adler/packer-templates,matsumana/packer-templates-2,sachalin/packer_centos,ody/packer-templates,ody/packer-templates,kaorimatz/packer-templates,d-adler/packer-templates,Pluto1010/packer-templates-1,reallyenglish/packer-templates,reallyenglish/packer-templates,matsumana/packer-templates-2,kaorimatz/packer-templates,sachalin/packer_centos,wporter82/packer-templates,wporter82/packer-templates