(PUP-1151) Hard code return of only production environment

This plumbs in the first step and getting the list of environments
returned. At the moment it is hard coded to only ever return the
prodution environment.
(PUP-1151) Inject source of environments

This pulls out the source of the environments from the V2::Environments
code and instead injects it from a "provide"d handler. The "provide"
method on V2 allows a handler to be constructed lazily, which is needed
when it needs to be instantiated with information that isn't known until
request time (in this case the source of the environments).