Add some support functions for clustering using PySAL

pg/.gitignore

@@ -1,4 +1,3 @@
-dist/
 test/regression.diffs
 test/regression.out
 test/results

pg/dist/crankshaft--0.0.1.sql

@@ -0,0 +1,5 @@
+CREATE OR REPLACE FUNCTION cdb_poc_xyz()
+RETURNS Text AS $$
+    from crankshaft.poc import xyz
+    return xyz()
+$$ LANGUAGE plpythonu;