update sources to github locations

sources.cfg

 [buildout]
-svn-zope-org = ^
 github = git://github.com/zopefoundation
 
 [sources]
@@ -19,9 +18,9 @@ Products.MIMETools = git ${buildout:github}/Products.MIMETools
 Products.OFSP = git ${buildout:github}/Products.OFSP
 Products.PythonScripts = git ${buildout:github}/Products.PythonScripts
 Products.StandardCacheManagers = git ${buildout:github}/Products.StandardCacheManagers
-Products.ZCatalog = svn ^/Products.ZCatalog/branches/2.13
-Products.ZCTextIndex = svn ^/Products.ZCTextIndex/trunk
-Record = svn ^/Record/trunk
-tempstorage = svn ^/tempstorage/trunk
-zExceptions = svn ^/zExceptions/trunk
-ZopeUndo = svn ^/ZopeUndo/trunk
+Products.ZCatalog = git ${buildout:github}/Products.ZCatalog branch=2.13
+Products.ZCTextIndex = git ${buildout:github}/Products.ZCTextIndex
+Record = git ${buildout:github}/Record
+tempstorage = git ${buildout:github}/tempstorage
+zExceptions = git ${buildout:github}/zExceptions
+ZopeUndo = git ${buildout:github}/ZopeUndo