Handle different cloud-init versions gracefully

Change loguserdata script to python to allow easy detection of which
version of cloud-init installed. Some logging was added to
part-handler.

Took out injecting the command to touch provision-finished in the user
data. This is now handled in loguserdata.py.

Note that up until cloud-init version 0.6.0, the user data is not
passed to part-handler. This behavior is why it's not possible to log
the provisioning process with older versions. (Technically could rely
on the redirection support added post 0.6.0, but having a separate
file just for provisioning seems beneficial.)

fixes bug 1072921

Change-Id: I9005a21bfb74f27208f9195a6e10e1d2b474e91f
Signed-off-by: Jeff Peeler <jpeeler@redhat.com>