here's a solution.
Just download this,
unzip it,
open a terminal,
cd to the folder you've unzipped and run:
./install_me.sh
when nautilus will open the ~/.local/share/applications folder just drag the "Mount Android MTP Filesystem" launcher to the Unity bar and you're good to go with it.
right clic and enjoy
to uninstall this solution:
cd to the folder you've unzipped and run:
./remove_me.sh
hope it helps!
Credits:
http://www.omgubuntu.co.uk/2011/12/how-to-easily-mount-the-galaxy-nexus-on-ubuntu-11-10-via-unity
http://blog.itsbilal.com/index.php/2012/12/connect-an-android-4-0-phonetablet-to-ubuntu-the-reliable-way/