Support Pillow

From <https://bugzilla.redhat.com/show_bug.cgi?id=896295>:

Fedora 19 is going to stop shipping python-imaging (PIL) and start shipping python-pillow instead.  Rationale can be found on the [feature page](https://fedoraproject.org/wiki/Features/Pillow).

pillow should be compatible with PIL at the code level but the import statement changes slightly.

PIL supports both of these:

    import Image

and

    from PIL import Image

Pillow only supports the latter form.