adds maxp algorithm

src/pg/sql/22_maxp.sql

@@ -0,0 +1,16 @@
+-- max-p regionalization
+
+CREATE OR REPLACE FUNCTION
+  CDB_MaxP(
+      subquery TEXT,
+      colnames TEXT[],
+      min_size int default 1,
+      initial int default 99,
+      geom_col TEXT DEFAULT 'the_geom',
+      id_col TEXT DEFAULT 'cartodb_id')
+RETURNS TABLE (region_class text, p_val numeric, rowid bigint)
+AS $$
+  from crankshaft.clustering import MaxP
+  maxp = MaxP()
+  return maxp.maxp(subquery, colnames, floor=min_size)
+$$ LANGUAGE plpythonu;