Add extra debug info

[sergio-costas]

This patch show extra debug info for DBus; specifically, when some DBus calls fail, it shows the called address, object and interface, to allow to identify the misbehaving application.

[sergio-costas]

@3v1n0 Can you review this when you have some spare time, please?

[3v1n0]

Cleaned up the long lines and squashed the commits, we should be ready to go!

Thanks