[76395676] Extend clj-config to support an idg-owned config file 

https://www.pivotaltracker.com/story/show/76395676 
[76395676] Extend clj-config to support an idg-owned config file 


Infra's cfg files have quoted values. So this doesn't represent the format of an actual `/etc/rentpath/environment.cfg`. I don't know if that's intentional.