Add tool to detect email inconsistencies

[akshaymankar]

[akshaymankar]

Initially when people have an old dist-newstyle and then build nix things, this will happen. So switching branches is going to be a little painful, but eventually it should not be a thing at all.

[fisx]

task:
build-intermediate
selected worker: concourse-worker-2
INFO[0000] building image
error: could not find wire-server/build/ubuntu: stat wire-server/build/ubuntu: no such file or directory
FATA[0000] failed to build: build: exit status 1
FATA[0000] failed to run task: exit status 1

seems unrelated.

[akshaymankar]

Superseded by https://github.com/wireapp/wire-server/pull/2840