added check for python <2.5 in setup file

setup.py

@@ -4,6 +4,9 b' from rhodecode import __platform__'
 
 py_version = sys.version_info
 
+if py_version < (2, 5):
+    raise Exception('RhodeCode requires python 2.5 or later')
+
 requirements = [
         "Pylons==1.0.0",
         "WebHelpers>=1.2",