composer is flaky in webpack

[starpit]

origin: kubernetes-retired/kui#584

• preview @demos/if.js fails because of a readFile for webpack bug with imports

• preview -c @demos/if.js fails for that bug, and a few other similar bugs

• app deployment doesn't work in webpack
  Composer client (in openwhisk-composer libararay) is implemented to grab credentials from local wskprops, so in Webpack mode, we need to pass the api_host and api_key in options (in apache-composer/lib/controller/client) based on window.localStorage or process.env.__OW_API_KEY or process.env.__OW_API_HOST

• clicking Deploy in compose foo.js fails because the composition persister uses tmp.file