Install scikit learn from git instead use egg

/reviewed-on nexedi/slapos!143

software/wendelin/software-dev.cfg

@@ -18,3 +18,8 @@ eggs += ${wendelin.core-dev:egg}
 # to installing non-dev egg
 [versions]
 wendelin.core =
+scikit-learn =
+
+# install scikit-learn git clone
+[scikit-learn]
+<= scikit-learn-develop