[repo] fix deprecation messages for stats and gc_stats

[cwconfig] use "foo not in bar" instead of "not foo in bar"

[debian] Add Breaks on a few cubes that need changes for 3.19 - mercurial_server is affected by composite deletion changes - forgotpwd relied on session data to be forwarded to notification view - registration hooks into the authentication stack

[hooks] run cascading delete hook later Applications may have their own before_delete_entity hooks that rely on the composite relations still existing.