Update required version of psycopg2

With issue4949, we need context management on connection and cursor,
this was introduced in psycopg2 version 2.5.

review24911002

doc/topics/install.rst

@@ -14,7 +14,7 @@ Prerequisites
     * python-dateutil (http://labix.org/python-dateutil)
     * polib (https://bitbucket.org/izi/polib/wiki/Home)
     * python-sql 0.4 or later (http://code.google.com/p/python-sql/)
-    * Optional: psycopg 2 or later (http://www.initd.org/)
+    * Optional: psycopg 2.5.0 or later (http://www.initd.org/)
     * Optional: psycopg2cffi 2.5.0 or later
       (http://github.com/chtd/psycopg2cffi)
     * Optional: MySQL-python (http://sourceforge.net/projects/mysql-python/)

setup.py

@@ -35,7 +35,7 @@ if minor_version % 2:
 if platform.python_implementation() == 'PyPy':
     pg_require = ['psycopg2cffi >= 2.5']
 else:
-    pg_require = ['psycopg2 >= 2.0']
+    pg_require = ['psycopg2 >= 2.5']
 
 setup(name=name,
     version=version,