Parameters from environment

[boesing]

Feature Request

Q	A
New Feature	yes
RFC	yes
BC Break	no

Summary

I do want to put some parameters into several environments to reduce the amount of files we do have locally.
I'd love to have something like symfony where I can use something like %env()%.

No clue if we do want to support the same notation and/or if it is already built-in into the ParameterBag which is used in this component. Any feedback would be awesome, imho it might be very helpful for some use-cases.