bus: always show messages we send
bus: add a temporary hard-coded policy to proxyd to make gdm work

gdm relies on the policy to deny its own requests to not deadlock. Given
that we currently do not enforce any policy in the dbus1 compat proxy
service this means that gdm will necessarily deadlock on our systems.

To work around this, enforce a fixed policy teomporarily, until we
interpret the legacy XML policy in full.

Booh, gdm, booh, for requring this and making me waste two days on
tracking this brokenness down.
man: fix description of is-enabled returned value