Fix sending messages to numeric stream names.

json_to_foo will raise a ValueError if the JSON passed to it is just a
string containing a number, e.g. "1".

Traceback (most recent call last):
  File "/home/tabbott/humbug/zephyr/views.py", line 711, in extract_recipients
    recipients = json_to_list(raw_recipients)
  File "/home/tabbott/humbug/zephyr/decorator.py", line 289, in json_to_list
    return json_to_foo(json, list)
  File "/home/tabbott/humbug/zephyr/decorator.py", line 282, in json_to_foo
    raise ValueError("argument is not a %s" % (type().__class__.__name__))
ValueError: argument is not a list

Fixes #776.

(imported from commit 0c123a610c009eda9004cf0b0b53d60695c4e8d5)

zephyr/views.py

@@ -708,7 +708,7 @@ def mit_to_mit(user_profile, email):
 def extract_recipients(raw_recipients):
     try:
         recipients = json_to_list(raw_recipients)
-    except simplejson.decoder.JSONDecodeError:
+    except (simplejson.decoder.JSONDecodeError, ValueError):
         recipients = [raw_recipients]
 
     # Strip recipients, and then remove any duplicates and any that