[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.

[devtools] set PGPORT/PGHOST when calling pg_ctl start Helps pg_ctl find the socket on squeeze, otherwise it looks in /var/run/postgresql.