Update PIL to use Pillow

[Metallicow]

PIL hasn't been updated in ages and other distros are using Pillow(friendly PIL fork) also.

It doesn't seem clear after all this time, whether the original author is ever going to return to PIL, so the next best thing is to use Pillow as it supports PY3 and provides numerous fixes and improvements/additions that PIL left hanging or never had realized.

Pillow is also actively maintained/developed.

https://github.com/python-imaging/Pillow