Readme example doesn't compile

[bvwells]

Hi Netflix!

It looks like the example in the readme doesn't actually compile as is.

Running the example in go playground I get the following errors:
./prog.go:22:18: undefined: env.Environment
./prog.go:38:19: cannot use "/tmp/edgarl" (type string) as type *string in map value
./prog.go:44:16: undefined: env.Environment

See https://play.golang.org/p/p-QYyb6xpG-

One possible set of fixes can be found here:

https://play.golang.org/p/rDcHu8xuBBG

Hope this helps!