Simultaneous mount of disk image

[RoganDawes]

Hi,

In the script on https://github.com/ckuethe/usbarmory/wiki/USB-Gadgets, you mount the file system locally on the USBArmory, but also export it to the USB host.

Since both the Armory and the USB host think they have exclusive access to this filesystem, and may write at any time, you run the risk of corrupting the filesystem. The filesystem should only ever be mounted by the Armory when the mass storage gadget is disabled.