Use firefox instead of opera

software/selenium/software.cfg

@@ -5,7 +5,7 @@ extends =
    ../../component/xorg/buildout.cfg
    ../../component/lxml-python/buildout.cfg
    ../../component/python-2.7/buildout.cfg
-   ../../component/opera/buildout.cfg
+   ../../component/firefox/buildout.cfg
    ../../stack/shacache-client.cfg
 
 versions = versions
@@ -30,7 +30,7 @@ parts =
    eggs
    instance-recipe-egg
    xserver
-   opera
+   firefox
 
 versions = versions