slapos-testing: Usage of undercore was deprecated

Fix usage of _ that was depreprated on the recipe, with the upgrade it it got broken.

software/slapos-testing/instance.cfg

@@ -97,6 +97,4 @@ mode = 755
 recipe = slapos.cookbook:wrapper
 command-line = ${phantomjs:location}/phantomjs-slapos
 wrapper-path = $${create-directory:bin}/phantomjs
-# XXX we must use "parameters-extra" (- instead of _)
-# when new slapos.cookbook will be used
-parameters_extra = true
+parameters-extra = true

software/slapos-testing/software.cfg

@@ -88,7 +88,7 @@ branch = master
 [template]
 recipe = slapos.recipe.template
 url = ${:_profile_base_location_}/instance.cfg
-md5sum = 10ffba4e2c0d119bbf9aabf3d71055e0 
+md5sum = 69a439b77b1fc8e89856c7ffc293d6b2 
 output =  ${buildout:directory}/template.cfg
 mode = 640