update version to 2.12.4

Author: vvolkl

conf.py

@@ -63,7 +63,7 @@
 # The short X.Y version.
 version = u'2.12'
 # The full version, including alpha/beta/rc tags.
-release = u'2.12.0-devel'
+release = u'2.12.4'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.