Issue24 (#42)

* Address issue #24
* Remove getReadCaches() & replace it with getCache()

Now whipper always follows XDG specifications. All changes were documented into the README file.

The changes introduced here aren't backward compatible so, after updating whipper, you may need to configure it again (old config file are retained, though).

morituri/test/test_common_directory.py

@@ -16,6 +16,3 @@ class DirectoryTestCase(common.TestCase):
 
         path = d.getCache()
         self.failUnless(path.startswith('/home'))
-
-        paths = d.getReadCaches()
-        self.failUnless(paths[0].startswith('/home'))