added python3 compatibility by catching the errors with xrange

[AlexFrazer]

#3

[pedro-teixeira]

+1

[pilosus]

Yes, please, merge that commit. Otherwise we have broken methods with xrange that don't work for python3. Even for python2 such a small range has a negligible performance advantage when you compare xrange with range:

$ python -m timeit -n 1000000 "import ip; ip.get_random_ip_v4_xrange()"
1000000 loops, best of 3: 7.86 usec per loop

$ python -m timeit -n 1000000 "import ip; ip.get_random_ip_v4_range()"
1000000 loops, best of 3: 8.09 usec per loop

[Narinas]

yes, it breaks with python3