correct dictionary format for normalizing

These changes allow an archetype to pass a dictionary as
simple as {'commodity_name1':Resource1} as the
request portfolio, and it can be normalized as needed to
interact with the DRE properly

cyclus/lib.pyx

@@ -1837,7 +1837,7 @@ cpdef dict normalize_request_portfolio(object inp):
         constrs = inp.get('constraints', [])
     else:
         commods = []
-        for name, reqs in inp:
+        for name, reqs in inp.items():
             if name == 'preference' or name == 'exclusive':
                 continue
             commods.append({name:reqs})
@@ -1855,10 +1855,11 @@ cpdef dict normalize_request_portfolio(object inp):
             if isinstance(val, ts.Resource):
                 req = default_req.copy()
                 req['target'] = val
-                if 'preference' in inp['commodities'][index]:
-                    req['preference'] = inp['commodities'][index]['preference']
-                if 'exclusive' in inp['commodities'][index]:
-                    req['exclusive'] = inp['commodities'][index]['exclusive']
+                if 'commodities' in inp:
+                    if 'preference' in inp['commodities'][index]:
+                        req['preference'] = inp['commodities'][index]['preference']
+                    if 'exclusive' in inp['commodities'][index]:
+                        req['exclusive'] = inp['commodities'][index]['exclusive']
                 commods[index][key] = [req]
 
             elif isinstance(val, Mapping):