Add datapipe for PackageKit in Locked state
Block late suspend if PackageKit is in Locked state
Add dbus debugging helpers

Make human readable strings from whole/parts of dbus messages.
Add module for tracking PackageKit D-Bus service and Locked property

Query PackageKit service state and properties on mce startup.

Track changes to Locked property while PackageKit service is available.

Handle PackageKit service starting up or exiting.

[mce] Add module for tracking PackageKit D-Bus service and Locked property
Merge pull request #122 from spiiroin/packagekit_module

Block late suspend when PackageKit is in Locked state