BUG: When using the library's restClient class. I got Error: only one instance of babel-polyfill is allowed

```
Error: only one instance of babel-polyfill is allowed
at Object. (/Users/jwang209/Projects/PDE/nodejs/ilorest-poc/node_modules/babel-polyfill/lib/index.js:10:9)
at Module._compile (internal/modules/cjs/loader.js:738:30)
at Module._compile (/Users/jwang209/Projects/PDE/nodejs/ilorest-poc/node_modules/pirates/lib/index.js:99:24)
at Module._extensions..js (internal/modules/cjs/loader.js:749:10)
at Object.newLoader [as .js] (/Users/jwang209/Projects/PDE/nodejs/ilorest-poc/node_modules/pirates/lib/index.js:104:7)
at Module.load (internal/modules/cjs/loader.js:630:32)
at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
at Function.Module._load (internal/modules/cjs/loader.js:562:3)
at Module.require (internal/modules/cjs/loader.js:667:17)
at require (internal/modules/cjs/helpers.js:20:18)
```
If I comment out the line here https://github.com/HewlettPackard/javascript-ilorest-library/blob/master/lib/index.js#L20

then the issue goes away.