no need future module for python2

fix missing StringIO

cps/fb2.py

@@ -4,8 +4,10 @@
 from lxml import etree
 import os
 import uploader
-import StringIO
-
+try:
+    import StringIO
+except:
+    from io import StringIO
 
 def get_fb2_info(tmp_file_path, original_file_extension):
 

cps/ub.py

@@ -10,7 +10,7 @@ import os
 import logging
 from werkzeug.security import generate_password_hash
 from flask_babel import gettext as _
-from builtins import str
+#from builtins import str
 
 dbpath = os.path.join(os.path.normpath(os.path.dirname(os.path.realpath(__file__)) + os.sep + ".." + os.sep), "app.db")
 engine = create_engine('sqlite:///{0}'.format(dbpath), echo=False)

cps/web.py

@@ -47,7 +47,7 @@ import db
 from shutil import move, copyfile
 from tornado.ioloop import IOLoop
 from tornado import version as tornadoVersion
-from builtins import str
+#from builtins import str
 
 try:
     from urllib.parse import quote