Don't require for CMD and EXPOSE to be defined in Dockerfile used for (#237)

deploying but allow those to be defined in upstream Dockerfiles

lib/read-metadata.js

@@ -74,20 +74,6 @@ module.exports = async function (path, {
       throw e
     }
 
-    if (!docker.some(cmd => cmd.name === 'CMD')) {
-      const e = Error('No `CMD` found in `Dockerfile`. ' +
-        'See: https://docs.docker.com/engine/reference/builder/#/cmd')
-      e.userError = true
-      throw e
-    }
-
-    if (!docker.some(cmd => cmd.name === 'EXPOSE')) {
-      const e = Error('No `EXPOSE` found in `Dockerfile`. A port must be supplied. ' +
-        'See: https://docs.docker.com/engine/reference/builder/#/expose')
-      e.userError = true
-      throw e
-    }
-
     const labels = {}
     docker
     .filter(cmd => cmd.name === 'LABEL')