Restore 2.5 support for the time being

.travis.yml

@@ -1,6 +1,7 @@
 language: python
 
 python:
+  - 2.5
   - 2.6
   - 2.7
   - pypy

flask/ctx.py

@@ -9,6 +9,8 @@
     :license: BSD, see LICENSE for more details.
 """
 
+from __future__ import with_statement
+
 import sys
 from functools import update_wrapper