This aims to lookup for Vmware Fusion required binaries (vmrun and vmware-vdiskmanager) in the system path first before falling back in the default Vmware Fusion installing path.
Thereby, the vmwarefusion docker-machine driver can now be used even if Vmware Fusion is not installed in its default location (with brew cask for example).
Signed-off-by: Jean-Christophe Lagache <jclagache@gmail.com>