Mount provider should not check existence of Fuse devices

When using the mount resource with a fuse mount, the provider will fail due to "device does not exist". Fuse devices in general cannot be checked for existence because:
a. Fuse filesystems have crazy devices and we can't have chef know about every fuse filesystem in existence
b. The device is usually given as "fusetype#device" which needs parsing

The easy solution is to exclude the check for Fuse. However, there are a already quite a few bugs about device existence checks so perhaps a better solution is to provide a directive for disabling the check altogether.