Fix the zipfile example for Python 2; and rename it.

The examples/csv/fuzz.py is actually testing the zipfile module,
so it has been renamed to reflect this. There are slight differences
in the Python 2 usage, which I've harmonised in the module.

examples/zipfile/fuzz.py

@@ -0,0 +1,23 @@
+import io
+import zipfile
+from pythonfuzz.main import PythonFuzz
+
+try:
+    allowed_exceptions = (zipfile.BadZipFile, zipfile.LargeZipFile)
+except AttributeError:
+    # In Python2, one of these had an inconsistent capitalisation
+    allowed_exceptions = (zipfile.BadZipfile, zipfile.LargeZipFile)
+
+
+@PythonFuzz
+def fuzz(buf):
+    f = io.BytesIO(buf)
+    try:
+        z = zipfile.ZipFile(f)
+        z.testzip()
+    except :
+        pass
+
+
+if __name__ == '__main__':
+    fuzz()