[bluez] Fix bluez-test dependency. Contributes to JB#17857.

Require a version of pygobject2 that provides D-Bus
introspection, so that simple-agent and other python
test scripts needing it work.
Merge pull request #41 from hmallat/bluez-test-dependency-fix

[bluez] Fix bluez-test dependency. Contributes to JB#17857.