debian: Branch off 3.5

Signed-off-by: Gergely Nagy <algernon@balabit.hu>
debian: Update the copyright file

Signed-off-by: Gergely Nagy <algernon@balabit.hu>
debian: Add mod-redis and mod-stomp packages

Signed-off-by: Gergely Nagy <algernon@balabit.hu>
debian: Bump the config version to 3.5

Signed-off-by: Gergely Nagy <algernon@balabit.hu>
debian: Update to the final 3.5.0rc1

Signed-off-by: Gergely Nagy <algernon@balabit.hu>