The card name (id) can be configured with udev rules to remain
constant based on where the device is plugged in even when there
mulitple of the same devices.
This is more in line with wayland and it allows us to create new
interfaces in modules without having to add anything to the type
enum. It also removes some lookups to map type_id to readable
name in debug.
Implement the device reservation DBus API.
When we acquire the device name, set our device profile to 'On'. This
adds our sources and sinks to the graph.
When we lose the name, switch back to 'Off' and remove our nodes
again.
Move the session mamager stuff in a directory.
Fixes#191
