clean the worktree before build document
add deploy-service.sh for downloading and running necessary scripts

Download Makefile and deploy.sh from github, if they don't exist in the
work directory. Then pass all the arguments to deploy.sh
add deploy.sh

 - It only works for travis-ci for now
 - It only works for master branch of R package for now
 - With deploy.sh in source directory of R package, run ./deploy.sh to
   prebuild the package and push to master-pkg