Finished up most of the record order validation and also checking

for all required records in a set. Added a controller class but
decided to put stuff in __init__ instead, at least for now.
Added a DateField which converts datetime.date into the proper
string format for EFW2 files (hopefully), this should still be
tested next week.

model.py

@@ -2,6 +2,7 @@ from fields import Field
 
 class Model(object):    
     record_identifier = '  '
+    required = False
 
     def __init__(self):
         for (key, value) in self.__class__.__dict__.items():