BLD: Increase the minimum pillow version to 2.1.0.

requirements.txt

@@ -3,5 +3,5 @@ numpy>=1.6.1
 scipy>=0.9.0
 six>=1.4
 networkx>=1.8
-pillow>=1.7.8
+pillow>=2.1.0
 dask[array]>=0.5.0

tools/travis_before_install.sh

@@ -40,9 +40,6 @@ fi
 # test minimum requirements on 2.7
 if [[ $TRAVIS_PYTHON_VERSION == 2.7* ]]; then
     sed -i 's/>=/==/g' requirements.txt
-    # PIL instead of Pillow
-    sed -i 's/pillow.*/pil==1.1.7/g' requirements.txt
-    WHEELBINARIES=${WHEELBINARIES/pillow/pil}
 fi
 
 # create new empty venv