Add options to Contiguity calculators

calculators.diff

Index: calculators.py
===================================================================
--- calculators.py	(revision 1396)
+++ calculators.py	(working copy)
@@ -788,6 +788,8 @@
 
         count = 0
         for district in districts:
+            if district.geom.empty:
+                continue
             if len(district.geom) == 1: 
                 count += 1
             else:
@@ -887,6 +889,7 @@
         districts = plan.get_districts_at_version(version, include_geom=False)
 
         calc = Contiguity()
+        calc.arg_dict = self.arg_dict
         calc.compute(**kwargs)
 
         self.result = { 'value': len(districts) == calc.result }
@@ -919,6 +922,7 @@
         districts = plan.get_districts_at_version(version, include_geom=False)
 
         calc = Contiguity()
+        calc.arg_dict = self.arg_dict
         calc.compute(**kwargs)
 
         count = len(districts) - calc.result