Add a QA config

[hethcox]

I love this starter and have used it on three different projects. One challenge I have is deploying a QA version with appropriate URLs for my QA resources. It seems that the prod.env.js values override the OS environment variables in my QA environment. Put another way, I'd like to deployed a QA distribution that used different resources than the PROD distribution. If I'm missing something, please correct me but, if not, could another deployment target be added to the baseline?