Cannot set filter parameters in changes() call

[mythsmith]

The Feed._validate method makes it impossible to pass arbitrary query parameters to a _changes filter design document when calling CouchDatabase.changes().

python-cloudant/src/cloudant/feed.py

Line 114 in 4435d84

if key not in arg_types:

If the key is not in arg_types, it should assume it is a custom parameter directed at the filter and hope. Maybe just check if it is an int, float, or str, as these are the only supported types for the query.

I suppose the same holds for Cloudant._db_updates().

[rajinib]

@mythsmith Thanks for bringing this to our attention. We will add this to our backlog and prioritize as needed.