修复若干bug，优化若干代码

utils/ImageStorage.py

@@ -0,0 +1,16 @@
+from django.core.files.storage import FileSystemStorage
+from django.conf import settings
+import os, time, random,hashlib
+from django.http import HttpResponse
+
+
+class ImageStorage(FileSystemStorage):
+    def __init__(self, location=settings.MEDIA_ROOT, base_url=settings.MEDIA_URL):
+        super(ImageStorage, self).__init__(location, base_url)
+    def _save(self, name, content):
+        ext = os.path.splitext(name)[1]
+        d = os.path.dirname(name)
+        md5hash = hashlib.md5((os.path.basename(name) + str(time.time())).encode("utf-8"))
+        fn = md5hash.hexdigest()
+        name = os.path.join(d, fn + ext)
+        return super(ImageStorage, self)._save(name, content)