lamp: install pycurl explicitly with ${pycurl:egg}

Otherwise it will be installed without our special part, using system
curl.

/reviewed-on nexedi/slapos!639

stack/lamp/buildout.cfg

@@ -150,6 +150,7 @@ location = ${buildout:parts-directory}/${:_buildout_section_name_}
 recipe = zc.recipe.egg
 eggs =
   ${lxml-python:egg}
+  ${pycurl:egg}
   slapos.toolbox
 
 [versions]