add bmo parser, some refactors

README.md

@@ -58,7 +58,7 @@ class MinimalBankParser(TransactionParser):
         return msg["From"] == "Minimal Bank <alerts@minimalbank.com>" and "Transaction Alert" in msg["Subject"]
 
     def extract(self, msg):
-        body = msg.get_body().as_string()
+        body = msg.get_content()
         amount = ...  # Extract amount from body
         date = ...    # Extract date from body
         payee = ...   # Extract payee from body