Update setup.py

fixes deprecation of sklearn in favor of current package name scikit-learn

Author: nmannheimer

setup.py

@@ -85,7 +85,7 @@ def read(fname):
             "requests",
             "scipy",
             "simplejson",
-            "sklearn",
+            "scikit-learn",
             "textblob",
             "tornado",
             "twisted",