Bump Pillow version to 2.3.0 to fix compilation issues
Bump Pillow version to 2.3.0 to fix compilation issues

Pillow didn't compile with FreeType 2.5.1 before 2.2.2 and 2.3.0 brought some
nice additions for handling TIFF files that I wanted to have available (i.e.
saving arbitrary tags).

htem/CATMAID,htem/CATMAID,fzadow/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID