If available use udisks2-inhibit to prevent automounting (#745349)

In order to prevent potential corruption of newly created file systems,
when available use udisks2-inhibit with gpartedbin execution to prevent
automounting.

Original report:

Xubuntu install fail due partition auto mount defeats Gparted
https://bugs.launchpad.net/ubuntu/+source/thunar/+bug/1078445

Some GNU/Linux distributions use the udisks2 "udisksd" daemon and have
udisks2-inhibit at a known location.  The known location is not in the
default PATH environment variable.

One known distribution that matches this criteria is xubuntu 14.04.

Interestingly neither kubuntu 14.04 nor ubuntu 14.04 appear to have the
udisks2 "udisksd" daemon running and do not suffer from this specific
automounting problem.

Bug 745349 - gparted wrapper script needs updated for udisks2