set own Proxy

[wangxdmm]

Thanks for your react-scripts-ts
But , I can not set up my own Proxy, The reason shoule be this :

I can not find proxySetup in config/paths.js
when I add this in config/paths.js It works (src/setupProxy.js)

Thanks a lot， I love this scripts-version for react

[jpavon]

@wQueryLoveMm can you create a pull request with this change?