loopback:example improvements - add more files, fix a bug

 - use `npm pretest` scaffolded by loopback-workspace (see https://github.com/strongloop/loopback-workspace/pull/93)
 - fix a bug introduced by yeoman upgrade
 - add LICENSE, README and create-load.js

/to @ritch  or @raymondfeng please review
/cc @ShubhraKar this patch adds `bin/create-load.js` to the output of `yo loopback:example`