Use mask for iptables marks in traffic shaping

[juruen@…]

To avoid collision amongst the iptables marks used along the eBox modules, we have to define which range of marks uses each module.

Traffic Shaping will use from 256 to 512 and it will use the 0xFF00 mask.

Note that the limit is 256, although this may seem short, the truth is that more than that or even something near to 256 will turn the GUI unusable.

[ejhernandez@…]

(In [6906]) Making ts stable and compatible with network marking closes #481 (spent 3)