Comment 10 for bug 217571

In /etc/udev/rules.d/README I noticed this:

[...] Packages do not generally install rules here, this directory is for
local rules. If you want to override behaviour of package-supplied
rules, which can be found in /lib/udev/rules.d, you can do one of
two things:

 1) Write your own rules in this directory that assign the name,
    symlinks, permissions, etc. that you want. Pick a number higher
    than the rules you want to override, and yours will be used.

 2) Copy the file from /lib/udev/rules.d and edit it here; you
    should generally only do this if you want to prevent a program
    from being run.
[...]

I didn't have much time to experiment with a local rules files, so I went ahead and edited directly this file:
/lib/udev/rules.d/50-udev-default.rules

And it worked for me. So my workaround for this problem is:
1) Open a terminal window
2) gksudo gedit /lib/udev/rules.d/50-udev-default.rules
3) Make sure the following line has MODE=" 0666" at the end:

# libusb device nodes
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}", MODE="0666"

4) Restart the computer

I am not familiar with udev rules and as such I am not sure what other problems this may introduce, I'd appreciate if anyone else can elaborate on this.