Create gentoo package

[Abbakus]

Create the ebuild for Gentoo system.

[Abbakus (abbakus)]

I will add a patch to the ebuild to solve bug #781705.

Will change this:
------------
 def prog(self):
  return self.settings.get("vdepath") + "/vde_plug2tap"
-----------
into this code:
-----------
 def prog(self):
  return "\"/sbin/modprobe tun && " + self.settings.get("vdepath") + "/vde_plug2tap\""
-----------
or some similar solution.

[Abbakus (abbakus)]

Remember to move the "versioning" code from "install.sh" to "setup.py" to have standard python package.