Revert "release: Drop envs attribute."

This reverts commit 886cf96f68172021d0ac9f8fbe32e4085b7487bb.

Right now, this is still needed for aszligEnv until we have refactored
it to be a proper module.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

Conflicts:
	release.nix
envs: Drop all envs except aszligEnv.

As written in 886cf96, we don't need them anymore.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>