Issues/169 ask user to confirm request state

(Do not merge until issue 1418 can be closed on Alaveteli)

* Sends request state updates to Alaveteli when the council updates the request state.
* Sends an email to the requestor asking them to update the state for the request (stored but not reflected on the website, sent to Alaveteli with the intention that it's treated as the definitive request state, overruling the council) when the council closes the request.
* Sends a lighter weight email to the requestor - without a link to the state page or details about escalating the case to the ombudsman - if the council have registered an intermediate state such as "assessing"



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