only cache discussion forum info for 5 minutes before flushing. This is needed for Studio backed courses that can add new discussion items at any point in time. Also we need to also set metadata fields (which are basically the same as what gets passed in the XML) as the forums expect those values as metadata

change over the 'get all discussion models' to use get_items() which is better supported in Mongo-backed stores

Fix forums in IE9; apparently it's just very strict about the charset being a valid identifier. utf8 is not a valid identifier, utf-8 is.

Also fixed up some random bugs with content_info, and changed pagination code a little. Needs comments service update for the subscribed threads API call.

following if it wasn't working before.

* has to be eager