[seleniumrunner] make seleniumrunner compile again.

It was blocked by a missing find-links. Using slapos.cfg stack helps in defining all those details.

software/seleniumrunner/software.cfg

 [buildout]
 extensions = buildout-versions
 
-extends = 
+extends =
    ../../component/xorg/buildout.cfg
    ../../component/lxml-python/buildout.cfg
    ../../component/python-2.7/buildout.cfg
    ../../component/firefox/buildout.cfg
    ../../component/dash/buildout.cfg
    ../../stack/shacache-client.cfg
+   ../../stack/slapos.cfg
 
 # develop += /opt/slapdev
 
-versions = versions
-
-find-links +=
-    http://www.nexedi.org/static/packages/source/slapos.buildout/
-
 parts =
+   slapos-cookbook
    template
    eggs
    instance-recipe-egg
@@ -24,8 +21,6 @@ parts =
    firefox
    xwd
 
-versions = versions
-
 unzip = true
 
 [instance-recipe]
@@ -79,10 +74,6 @@ Flask = 0.8
 # slapos.cookbook==0.42
 PyXML = 0.8.4
 
-# Required by:
-# hexagonit.recipe.cmmi==1.5.0
-hexagonit.recipe.download = 1.6nxd002
-
 # Required by:
 # slapos.cookbook==0.42
 inotifyx = 0.2.0