Originally written Bilal Akhtar a Google employee and explained in some more detail here allows you to mount an Android device via terminal.
And repackaged on the WebUpd8 unstable repositories with a handy unity icon launcher to quickly mount or un-mount as needed, more info here.
To install run the following commands.
sudo add-apt-repository ppa:webupd8team/unstableVoila!
sudo apt-get update
sudo apt-get install go-mtpfs go-mtpfs-unity