Please add a README note - runs under python version 2, and not python version 3

[thx1111]

With Python 3.6.2, with Arch Linux:

$ python ./unkdz.py -f D41520f_00_0110.kdz -l
Traceback (most recent call last):
File "./unkdz.py", line 310, in
kdztools.main()
File "./unkdz.py", line 291, in main
self.partList = self.getPartitions()
File "./unkdz.py", line 126, in getPartitions
buf = self.infile.read(self.dataStart - self.headerEnd - 1)
ValueError: read length must be positive or -1

Instead, this requires:

$ python2 ./unkdz.py -f D41520f_00_0110.kdz -l
[!] Warning: Data between headers and payload! (offsets 825 to 0)
[+] KDZ Partition List (format v2)
=========================================
0 : D41520f_00.dz (1261287181 bytes)
1 : LGUP_8x10_8x26.dll (1595904 bytes)
2 : (0 bytes)

Please add a note to the README, regarding the required python version.
Thanks.