Allow the olefile dependency to be optional

Support for plugins requiring olefile will not be loaded if it is not
installed. Allows library consumers to avoid installing this dependency
if they choose. Some library consumers have little interest in the
format support and would like to keep dependencies to a minimum.

Tests/test_file_fpx.py

@@ -1,8 +1,14 @@
 from helper import unittest, PillowTestCase
 
+try:
     from PIL import FpxImagePlugin
+except ImportError:
+    olefile_installed = False
+else:
+    olefile_installed = True
 
 
+@unittest.skipUnless(olefile_installed, "olefile package not installed")
 class TestFileFpx(PillowTestCase):
 
     def test_invalid_file(self):

Tests/test_file_mic.py

@@ -1,10 +1,18 @@
 from helper import unittest, PillowTestCase, hopper
 
-from PIL import Image, ImagePalette, MicImagePlugin
+from PIL import Image, ImagePalette
+
+try:
+    from PIL import MicImagePlugin
+except ImportError:
+    olefile_installed = False
+else:
+    olefile_installed = True
 
 TEST_FILE = "Tests/images/hopper.mic"
 
 
+@unittest.skipUnless(olefile_installed, "olefile package not installed")
 class TestFileMic(PillowTestCase):
 
     def test_sanity(self):

requirements.txt

@@ -15,6 +15,7 @@ docutils
 jarn.viewdoc
 nose-cov
 nose
+olefile
 pep8
 pyflakes
 pyroma

setup.py

@@ -780,7 +780,6 @@ try:
           include_package_data=True,
           packages=find_packages(),
           scripts=glob.glob("Scripts/*.py"),
-          install_requires=['olefile'],
           test_suite='nose.collector',
           keywords=["Imaging", ],
           license='Standard PIL License',
@@ -806,4 +805,3 @@ which was requested by the option flag --enable-%s
 """ % (str(err), str(err))
     sys.stderr.write(msg)
     raise DependencyException(msg)
-