Added WORKDIR to Dockerfile.
Added WORKDIR to Dockerfile.

tianzhidao28/ubuntu,retroconduct/ubuntu,the1sky/ubuntu,Christopher-Chopin/ubuntu,dockerfile/ubuntu,mj19910923/dockerfile.ubuntu.base,pdeslaur/ubuntu,ossianpe/docker-build-centos,ruige123456/5-25,rednut/docker-ubuntu,jbng/nodejs-es,liujuncheng/dockerfile-android