This patch moves all of dbus code (service, dbus extensions) to the CheckBoxNG sub-project. This removes the heaviest dependency and unstable but external API from PlainBox, thus facilitating PlainBox release into Ubuntu and Debian.
Most of the changes were direct renames (followed up import and docstring changes). I also renamed dbus to dbus_ex to clearly indicate that it is an extension to the dbus library rather than a dbus implementation of any API (which implemented in the serviece module)
Unit tests were updated to take into account the move of the 'service' sub-command. PlainBox reference documentation was altered not to mention dbus anymore.
Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>